[Freak_NL]

> […] but I guess that's too obscure of a "market" to cater too

Oh no, this is on purpose. WhatsApp, Signal, etc. want to maintain control of the clients at all costs because of user tracking and monetization. If this wasn't the case, they would allow some form of non-smartphone access. As it is they keep their API's closed and ban anyone trying to use any form of third party tools.

In the case of Meta (WhatsApp) this is about keeping their silo-suite closed. People may hate Facebook, but if they can keep these users via the popular WhatsApp, they can keep up their numbers. What Signal really wants is anyone's guess. Something to do with that shifty cryptocoin I guess.

> I just want the freedom to use an "alternative" system like my Linux desktop or maybe some eclectic device like PinePhone or those modern PDA things or whatnot […]

Absolutely.

[Beltalowda]

Maybe; I don't know. Telegram has the same incentives (and I believe they have some crypto wazamabob as well). I think it's much more likely that it's just easier for them: abuse is a serious issue and the more "closed" a platform is, the harder (not impossible, just harder) it becomes to abuse it (see: email). And not having to worry about third party integration/APIs, compatibility, documentation, etc. also makes their lives just easier.

Getting all of this to work well with E2E requires extra thought (how do you make messages available on two devices?); Telegram hasn't nailed that either. I don't especially care about this, but a lot of people do.

Essentially, there are basically no practical upshots for them, and it's just more effort.