At least some of it is shitty companies either neglecting to optimize or even outright sabotaging their own sites to try and force you to install their data harvesting app so they can sell more of your data for profit.
The rest is just lazy devs not optimizing because they’re lazy and/or underpaid and overworked.
I highly recommend VLC
How about now?
We did it Lemmy! We’ve reached an arbitrary number of posts.
LPT: Don’t use reddit because it’s a fucking dumpster fire.