I declined the first flag you showed, it was on this answer.
The answer was pointing out the question was a duplicate (and where to find the answer), and there (over time) were nine total flags on that answer, and all of them pointed out that it was 'not an answer'. Yet none of those that flagged the answer did anything about the question.
So, in this particular case, the problem wasn't the answer, it was that the question was a duplicate.
Also, if you argue that you flag link only answers because link-rot, would that link-rot really extend to other Stack Overflow links?
Just some observations around that particular flag.
In the second flag, it was once again against an answer that points out this question had already been asked before (and answered, incidentally).
Yet this time, the question was not closed as a duplicate.
I'm starting to see a pattern.
"Not an answer" flags and answers with only links have traditionally been 'easy pickings' for someone wanting to boost their flag rate. They're rarely declined, and they're easy to find. Look for a short answer, or an answer with a link (and short) and you probably have a good candidate for one. Look for an answer with a question mark in an SEDE query and that can probably help you find some more.
The problem is, we don't need people to flag things that follow a set formula. If they're that prevalent and that's the criteria people use to flag them, then we can automate that process:
- "Answer less than 100 characters containing a link" - Link only answer
- "Answer with Question Mark" - Not an answer
- "Answer containing link to another Stack Overflow question or answer" - Link only Answer, or Not an answer, depending.
I'm glad there are members of the community that want to help us clean up. What we really need help on is the thousands and thousands of questions each day that get asked that probably already have answers, or aren't written well enough to be answered, or even the sock puppet rings that pop up. Those are things that aren't trivial to automate.
Having addressed the specific flags you've asked about, let me directly address your general question:
Different moderators handle it different ways. I personally think Link only answers are answers, they're just not very good answers. I think that before you flag them, you should leave a comment telling the user to improve their answer by editing in salient details from the link.
I also think it's a poor user experience to post a link and just have it summarily deleted without comment. If the thousands of users that flag posts every day seemingly don't have the time to leave a comment before flagging one post, what makes you think the 10 moderators handling 2500 flags a day will have time to leave a comment on each and every one?
It all comes down to what you expect us to do about link only answers.
Do you expect us to delete them? If so: why? We can build a tool that just doesn't let people post short answers containing a link. There's no reason to make that flaggable.
Do you expect us to leave a comment? Again, why? Shouldn't you have done that before you flagged? If you did just leave a comment, then why flag? I'm just going to decline it because the user needs time to act on your advice.
Overall, I understand that this is a contentious issue. You (collectively) want a clean site, and you want it now. I understand that. I want a clean site. But I want a clean site that people want to use. A new user coming in and posting a helpful link is not going to want to stick around if his content is deleted just because it was a link. They especially won't want to stay around if people don't inform them it's a bad practice.
Contrawise, they might stick around if people engage with them or even edit their answer to include the relevant information.
The rule shouldn't be "Flag everything that doesn't meet criteria X", the rule should be: "Engage, and if that doesn't work, flag."
If the community isn't willing to take on that little extra work with its thousands of members, then it's doubly unlikely this site would be successful putting it on the backs of its 10 moderators.