SO doesn't really gatekeep; anybody is free to ask any question. Questions may get closed (and deleted if they are spam/useless), but SO faces a stream of questions without reprexes, duplicates, and more. Some get fixed, some get closed, and some unfortunately become tumbleweeds, which is really worse than getting closed as a duplicate, as the asker never gets an answer.
As far as this site goes,
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When a question has a good reprex and isn't a very common one, the community should perhaps respond, "Hey, this is a good question! You should ask it on SO," which gives the asker a confidence bump and makes it easier for people to find the question later.
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If the question is a very common one (e.g. one of SO's r-faqs), linking to the canonical question on SO, e.g. for joins or long to wide form or summarizing multiple variables or making lists of data.frames can be really useful. There's not really a point in deduplicating here, but there is a point in directing the asker to a set of solid answers. Translating the answer to their context (i.e. answering) is nice as well, but sometimes pointing askers to the right resource is actually all they really need.
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Other questions (opinion-based, looking for tools, etc.) fit more neatly here than SO.
The SO API is good, and these could be nailed down to a particular set of parameters (say top 10 Qs and As with most votes on a given set of tags), so this wouldn't necessarily be complicated if there's interest. The top questions usually get answers, though, so they're more use for reading than answering, if that's the intent.
If bold, it's not uncommon. For it to be useful, it has to be followed with a distinction, though. I see a lot of XY questions that make that claim but don't illustrate a difference in their reprex, and the difference is only teased out after lots of comments (if the question even gets that far).