One criterion that may be a useful distinction is whether it actually, directly answers the question/solves the problem, or just provides a starting point for the OP to research their own answer.

Most link-only answers, link + a couple of sentence answers, or just couple of sentence answers, refer to a tool or general approach but don't explain how to actually solve the problem using it. So it doesn't answer the question (not an answer), rather it's a helpful suggestion (comment).

So for these, there is a criterion that can serve as the basis for a flag, then the result depends on whether the moderator agrees.

Two other kinds of low quality answers:

• Pablum answers (trivial generic information that may be technically true but basically useless).

• Duplicate answers (recycling what someone else has already answered in a less useful form).

Perhaps a case can be made for some pablum answers that they are just comments and flag them on that basis. However, these two categories can both meet the definition of an answer and their value is in the eye of the beholder. It isn't clear that there is a defined basis for deleting them, at least one that doesn't involve a value judgement and potential difference of opinion.

The best tool, in this case, may be downvotes. Adding comments about what is wrong with the answer and how to improve it may lead to improvement in some cases. The comment will also call attention to the problem and others may notice it, agree, and downvote. Downvotes can be better than deletion in some respects. Deleted answers are gone. Downvoted answers remain as an example of what not to do (and the comments explain why not to do it).

One criterion that may be a useful distinction is whether it actually, directly answers the question/solves the problem, or just provides a starting point for the OP to research their own answer.

Most link-only answers, link + a couple of sentence answers, or just couple of sentence answers, refer to a tool or general approach but don't explain how to actually solve the problem using it. So it doesn't answer the question (not an answer), rather it's a helpful suggestion (comment).

So for these, there is a criterion that can serve as the basis for a flag, then the result depends on whether the moderator agrees.

Two other kinds of low quality answers:

• Pabulum answers (trivial generic information that may be technically true but basically useless).

• Duplicate answers (recycling what someone else has already answered, especially when in a less useful form).

Perhaps a case can be made for some pabulum answers that they are just comments and flag them on that basis. However, these two categories can both meet the definition of an answer and their value is in the eye of the beholder. It isn't clear that there is a defined basis for deleting them, at least one that doesn't involve a value judgement and potential difference of opinion.

The best tool, in this case, may be downvotes. Adding comments about what is wrong with the answer and how to improve it may lead to improvement in some cases. The comment will also call attention to the problem and others may notice it, agree, and downvote. Downvotes can be better than deletion in some respects. Deleted answers are gone. Downvoted answers remain as an example of what not to do (and the comments explain why not to do it).

As @killermist points out, a pabulum answer could be appropriate, so downvotes need to consider the context of the question.