We know there's a big problem with addictive ux in general.

And of course we know that small changes increase engagement/addictiveness.

Html interfaces are easily configurable, technically.

The fact companies at least don't offer easy ways to configure websites to be less addicting, and some even block those, does tell us something.

Exactly correct - there is no way to disable the infinite scrolling reel nonsense in Snapchat while still allowing messaging. So, my son is either cut off from his friends or gets crap shovelled into his eyes. This is a business decision: to leverage their having insinuated themselves between him and his friends against his mental health. Ban it all immediiately