I'm not saying that the facts you are pointing to are wrong (although it's hard to argue the underlying evidence for your argument if you supply no evidence), but your way of addressing them is not correct.
The purpose of moderation is the application of existing policy.
Similarly, the police do not decide on what is illegal, they mere apply the existing legislature.
Your argument points out that there is a discrepancy between the policy and the moderation. You claim that there are many examples of the moderators not applying the established policy. If this is the case, then we should be reevaluating moderation, not the policy itself.
Similarly, if the police hardly ever manages to capture murderers, does not mean that we should revoke the laws on murder, simply because the police fails to enforce these laws like they should.
From the way you phrase your question, I infer that you do not think that the policy is wrong, but rather that it needs to be enforced better. So for the purposes of this answer, I am going to address ways to improve enforcement by moderators.
If my inference is incorrect, and you do think that the policy is wrong (regardless of how it is currently enforced), then you should argue against the policy on principle of it being wrong, not point at issues in moderating the established guideline.
Whenever we create a rule, there's an important question to ask: Can we apply this rule globally, or do we need to observe the context before we can say whether the rule is violated?
Moderators should only really be involved with the latter. Moderators are there to interpret the context and evaluate whether every specific instance they come across is a actual violation of the rules.
The moderators should not be tasked with enforcing blanket statements. Frankly, it is a waste of their time, because blanket statements can be enforced by the website without requiring human effort.
I think it's fair to say that moderation only deals with rules which cannot be accurately enforced by a machine. This is why moderation exists in the first place, because some rules factor in "the human element", which machines are incapable of evaluating.
I refer back to your question, where you stated the following:
IIRC, using profanity was only allowed when discussing the word itself, or if it was part of a quote, or a proper name of some place, but even in those cases it was expected to have a few letters replaced so as to avoid having the sites placed on "adult only" internet filters.
Going by this statement, the word "fuck" should never appear on the site. If its use cannot be avoided, it should be written as "f*ck" or "f***", even if the word is used in an innocent context (e.g. a semantical discussion or a direct quote from a script)
I disagree with this notion that swear words should be explicitly banned from the SE community unilaterally. For me, this is part of a larger opinion about the necessity of censorship altogether; but that is not the current topic of discussion.
If what you say is indeed the case, we should not expect the moderators to check all questions for the occurence of this word (or any other banned words). The website itself should refuse any question, answer or comment that uses this word, since there is literally no context in which its use would ever be deemed acceptable (going by your interpretation of the rules).
So if your argument is correct, then you should also agree that the moderators should not be tasked with this job. They are needed to moderate context-specific issues; and you're arguing that swearing should always be avoided regardless of context.
Although I admit this is somewhat of a pedantic niggle, you also contradict yourself:
it's easy enough to use the search box to find hundreds of questions containing uncensored, and often unnecessary, profanity on most sites
The fact that you don't consider all usages of the swear words that you come across as unnecessary, contradicts your statement that all usages should be banned globally.
For the continuation of this answer, I am going to assume that the absence of such a global rule implicitly proves that swear words are allowed on the site in a proper context.
If that is not the case, then someone needs to develop a text filter for post submission. This should not land on the moderators' shoulders.
Another point that is essential to the validity of your claim: your evidence. I will again let you speak first:
I'm not going to pick on any specific situations, it's easy enough to use the search box to find hundreds of questions containing uncensored, and often unnecessary, profanity on most sites, and, of course, you can find all the profanity across all sites using Google.
I followed your advice, and had a cursory browse. I checked for the following words:
- The F word
- The C word
On the following sites:
- Movies & TV
- English Language & Usage
Just like Catija already confirmed in an earlier comment, the overwhelming majority of hits are "innocent" uses of swear words.
- Direct quotes, or the paraphrasing of direct quotes
- Discussing word etymology or usage (e.g. why the C word is less offensive in Australia compared to America)
- Discussion topics on swear words and censorship
- Intentional translation between real swear words and minced oaths.
It's really hard to find actual transgressions here. The usage of swear words in the contexts that I listed here can all be considered acceptable: they either quote others (as a matter of undeniable fact) or discuss the word, rather than apply its meaning.
All in all, I would have to commend the mods for doing such a commendable job. The fact that I struggle to find any real cases when explicitly looking up swear words, should prove that the mods are doing an adequate job.
If you think that the policy should change, then you should address the policy and not just point at flaws in the moderation of the policy.
If you think that some swear words should be banned from the site on a global level, then you should take that up with its developers. This is not part of the moderator tasklist.
If you think that there is currently a lack of moderation for the established policy, then I would like to see some evidence to justify that claim. For as much as I've been looking, there is little to no offensive material to be found.
You requested (in the comments) that I prove that no such thing exists; and I'd like to repeat here that proving a negative is impossible. The burden of proof lies with you, if you're the one bringing up the subject.