>Thing is, Heyuri of 2020 was way smaller and way slower than modern Heyuri
It was only slightly smaller and slightly less active than today. Off-Topic in July 2020 had 3664 PPD, versus June 2023 having 4336 PPD - that's 84% as active! (and also not accounting for the fact that Heyuri's activity was distributed between many more boards back then)

If anything, 2020 Heyuri felt more active since all the replies would come in almost immediately after a thread was made - this was due to how prevalent the dicksword with the webhook was, as well as the Overboard which allowed you to view all posts on the site in one place

>And page 0 is full of porn dumps
The amount of pr0n on Off-Topic is about the same as it ever was - and in 2020 there were also pr0n/moe-dumping boards liek /h/, /c/, /l/, /g/, etc. (which were all eventually merged with Off-Topic, so enjoy teh sexy picz!!!)

>When there used to be only like 4-5 pages that stayed up for days
R u sure u were even on Heyuri in 2020?

Cuz back in 2020 we used to have INFINITE PAGES™ and no time-based bump limit at all - hence kuz getting mad about necrobumping a couple of times, until eventually a 3-day bump limit was imposed to keep things fresh and emphasize the creation of new threads over lingering in old ones (this was adjusted last year to 7 days to account for Heyuri being much slower... )