The phenomenon you inquire about is really happening, independently of the increase of the number of participants and independently of seasonal effects.
Here are three accepted answers I gave, accompanied by their date and number of upvotes:
https://math.stackexchange.com/a/63206/3217 $\;$ (2011, accepted, 52 upvotes )
https://math.stackexchange.com/a/98124/3217 $\;$(2012, accepted, 54 upvotes)
https://math.stackexchange.com/a/122826/3217 $\;$ (2012, accepted, 47 upvotes)
And here are three answers I gave in 2017 with the corresponding data:
https://math.stackexchange.com/a/2365941/3217 $\;$ (accepted, no other answer, zero upvote)
https://math.stackexchange.com/a/2357656/3217 $\;$ (not accepted, no other answer, zero upvote)
https://math.stackexchange.com/a/2245700/3217 $\;$ (not accepted no other answer, zero upvote)
My answer to this other 2017 question
was accepted (by the OP who kindly called it "elegant and clear"), but the question was then closed (which might partially explain the zero upvotes) under the absurd pretext that it was "unclear", while it actually is crystal clear for anybody with a minimal competence in algebraic geometry.
The crucial point is that the 2017 answers were, from my point of view, at least as difficult and technical as those in 2011 and 2012, and the absence of answers from other users tends to confirm that these recent questions were not especially easy to answer.
I don't intend at all to quit this wonderful site of ours, but the absence of thanks or acknowledgment from the OP, and the lack of comments by other users will inexorably lead me to leave an answer only when I feel that I might, for some reason, need it as a reference.