I think that we should define a best-practise for how to handle answers to questions which are ... well, not answers to the OP.
This is motivated by my own uncertainty: on the one hand, I like to help others who ask questions, and this implies to really take the OP seriously. If he makes it clear that he wants a (say) tikz answer, I would think twice before even considering to post a non-tikz answer. On the other hand, I see that this site is also about building a knowledge base.
These goals are in conflict: a knowledge base is best if it has lots of different points of view whereas the OP often has a specific goal what he intents to do with the question.
One examples which always comes to my mind is that the OP might have a huge document which is built with a specific package - and for reasons of consistency and learning time etc etc, he might want to avoid to use / learn / evaluate a new package which is unrelated to his previous attempts. After all, it is always easier to make incremental changes rather than beginning again from scratch and maintaining two worlds. To be honest, I would feel as if some answerer did not take me seriously if I receive an answer which is not an answer.
This question is largely motivated by the fact that I stumbled over two related meta questions:
-> here, the OP downvoted an answer for which he felt... well, perhaps he felt offended. I can understand him as the "offending" answers are unrelated to his question. If I where him, I would probably try to ignore the answers. Or would I downvote them? I am unsure. Perhaps I would (had I not read this meta question).
Both touch the topic, although their point is not to archieve a best-practise, but to deal with the symptoms.
So, back to the discussion: what should be(come) the best practise for answers which are not answers to the OP, but parts of building a knowledge base? Should these answers be marked in a special way such that the OP does not feel offended? Should the question be retagged such that a pstricks answer to a tikz question can be found by the search? I am sure that we would want to have the highest possible quality for the cross-references.
Would this mean that, for example "tikz / pstricks /metapost" are actually kind of aliases to the same tag (!?)