[Springtime]

I agree about more specific definitions of what is being referred to in discussions under the umbrella term 'social media', particularly given those pushing for regulation.

A couple things that stand out in discussions about social media negative consequences are: service-led algorithms and UX which actively fuel addictive patterns, an emphasis on a single and often IRL identity (Zuckerberg famously saying there should only be a single user identity[1]) and audience reach which is far too broad for various content.

On Discord people often become familiar with other users via their pseudonymous handles, even sharing IRL details as they're comfortable. However a few things help with this: no leaderboard-style gamification of posts like there is with Twitter or Reddit, chat is inherently lower stakes and the scope is limited to that community not the wider internet.

Traditional forums are interesting since I know various who were addicted but in a user-led rather than service-led way (ie: they've been addicted through habit of non-gamified checking of content/participation). Even expressing having anxiety posting threads due to the expectations of peers. However the benefit is still an awareness that the primary audience is mostly an in-group of (mostly friendly) peers. Whereas on Twitter for example, a user may say something for a specific intended audience but someone in bad faith re-contextualizes it and initiates dogpiling—which is an inevitability of almost any community but for sites with such broad scope is extremely difficult to moderate.

Like you mentioned, on Reddit there is almost zero emphasis on the user, whether as an OP or commenter, so there's much less interpersonal community building but OTOH much easier distancing from self 'performance'/anxiety.

[1] Some critique: https://news.ycombinator.com/item?id=37284960