@EverydayMoggie I suspect it’s what a non-technical person is capable of in terms of computer “hygiene”. The last two cases happen to be 2017 iMacs with 8GB of RAM. The “slowness” was due to memory pressure from so many extra, generally unused or unknown (to the user) things needless running.
The good news is that some cleanup and less than $50 of more RAM can keeps these machines useful for another couple of years.