I understand, I really do. I wish popularity contests didn’t break out occasionally and stir up trouble, and I wish voters would leave them to die down faster after a close.
By and large, the activity does drop off though. And it doesn’t really encourage asking that kind of question on purpose. Answering it might be encouraged a bit, but those who don’t practice the skill of backing up their answers are simply letting others surpass them as writers of quality answers.
But most importantly, the cure is worse for the community than the disease.
Policing answers is awful, dirty work for mods, and often is worse for the site than some undeserved rep. On balance, it’s better to just let voters be a little irresponsible sometimes.
Having done this duty before, it sucks.
The situation: A popular question, with lots of activity, and many answers that people like.
To police that, mods have to do a close read of word counts in the tens of thousands, plus comments and possibly revision histories.
For each post, make a difficult judgement as fairly as possible on whether posts are meeting the GS/BS standard. Then decide what to do: nothing, cite-banner, comment only, banner + comment, delete, or deleted + comment. Then if a comment is involved, compose a quality comment that could lead to a positive outcome.
All while considering that passions and personalities are in play. And the more the page has exploded, the greater that factor is.
Then get ready to deal with the backlash that’s inevitable when popular posts get moderated.
Among the backlash too is always a small but numerically significant fraction of active users who experience this so badly that it’s reason to resent the mods involved, and that’s long-term pain for the site.
The entire process is exhausting and a minefield.
Doing all that is rough and draining at the best of times: when doing it to try avoiding closing a question as obviously drawing primarily unsupported opinions.
Doing all that after a question gets a Primarily Opinion-based close is just as dirty and has much smaller benefit.
Even popular closed questions aren’t huge rep generators
I have a lot of answers and have answered a few in my time that in hindsight I should have not (because it was destined to be closed) or that I disagreed with the close. And they’re not really big rep generators after the initial activity.
Closed questions just don’t get the attention and activity of the same question that’s open. It bumps far less, inviting fewer voters.
On balance, close then ignore is better for the site and community
Some undeserved rep is a small price to pay to avoid the drain of community goodwill and moderator energy.