This issue has come up again and again with different results depending on which moderators/users saw the question first. Most recently,
- Please blacklist the [problem] tag ... again
- Remove "problem" tag
- Tag ban request: [problem] and [problems]
Let's take the definition of problem from dictionary.reference.com:
any question or matter involving doubt, uncertainty, or difficulty.
Stack Exchange consists of Question & Answer expert communities. As such, every question on here is due to some kind of problem, error, obstacle etc. Be it programming, parenting, academia.
Having the tags problem, issue, warning and error in the auto-complete tag form just prevents users from thinking a bit about tags that are actually appropriate for their questions.
If the tags were merely removed from all current questions, some users would undoubtedly re-enter them at a later date. Thus, I'd argue in favor of blacklisting all current and future use.
The tags warning and error might seem appropriate for certain cases, i.e. as compiler warning or gcc error when dealing with messages themselves. However, compound tags compiler-warning and gcc-error (cf. command-line) seem way more useful than polluting the global tag space, so to speak.
In my subjective anecdotal experience, it's usually these more informed questions that don't use overly broad tags such as warning or error to begin with, because the warning/error message is usually included (in part) in the question title.
While I'm most active on StackOverflow and Electronics SE -- hence my examples -- I consider these tags even harmful to most expert community sites.
Just consider hypothetical examples Parenting SE kindergarten problem, Academia SE ethics issue. These tags might easily and misleadingly be used and add no value to the questions or the tag system as a whole.
