No, please, no!
Or rather... thank you for asking! But on reflection, I disagree that we should allow big lists as a matter of policy.
A Stack Exchange site is not supposed to be a forum. In general, answers should be complete (although of course, very often, multiple good answers are possible, offering different approaches).
Very occasionally, there may be a need for a catch-all question that requires a more collaborative approach, a canonical post. A canonical post, in my opinion, is (generally) not, and should not be, a big list, but an attempt to cover all angles of an issue comprehensively.
The post you linked to is a case where a big list is justified, because
- the structure of the knowledge being shared lends itself to this format
- each answer can be complete in itself as an item in the list
- it would be impossible to incorporate all these answers into a single post or for one person to do all the work of compilation
None of the examples of questions here that you mention would work as a big list in my opinion.
Take the example of Do vegan instruments sound different from traditional instruments? which has been mod-closed by an SE staff member. We should assume that was done for a good reason. Can you imagine the big list of answers to this post? "In my experience, drums made from synthetic skins rather than traditional goatskin usually..." It could be a forest, it would go on and on and on and on. That question is too broad for sure, and answers would tend to be opinion-based too.
Considering Vegans: Besides supplements, what can substitute for Calcium? there is no need for a big list here. One or two or three posts by experts could cover all the significant sources.
This How much money would we save from going vegan? is unanswerable I think, though there might be several good questions in there that could be asked separately.
My view is that it is extremely unlikely that any area of knowledge about vegetarianism and veganism will lend itself to a big list format (which can make sense for knowledge about other topics, such as maths). If a post invites a big list, it is almost certainly too broad or polling for opinions, and those are classic close reasons.
That said, my imagination is limited; perhaps a question will come along that really does justify a big list, and that will be fine by me. But positively encouraging big-lists at this stage by making a tag and an inviting meta post is asking for trouble!
