Yeah, the continued upvotes for the same old questions doesn't surprise me, doubly so given the nasty culture of trying your best to close all new questions. Today, if someone posts a question, it will be closed as a duplicate (whether or not it actually is), or as too broad or too narrow. My main SO contribution in the last several years has been votes to re-open, which don't tend to get enough to actually re-open.

My real surprise isn't the continued flow of points, just the apparent stasis. I could imagine being at 0.003% by now, for instance, from this phenomenon.

Some of my oldest answers have hundreds of votes and required minimal effort to answer well... some of the newer answers have less than ten votes, since they're much more niche (even if they take 10x the effort to answer well).

A lot of the early broad answers got those huge upvote counts and make the early users who answered them stay in the top percentiles.

There really should be some karma decay system to prevent early users hogging 5-figure reputation. I didn't do much there in the last 5y but I am still way up in reputation.