Does Matrix encryption scale? Telegram rooms have a huge number of participants. Also last time I looked into this, Matrix encryption was also an opt in.
Many people seem to think that Telegram tries to be a Signal or Matrix replacement. I dont think Telegram tries to be any of that. If anything you can compare it to Discord, except much better.
To enable synched e2e conversations accross many devices you also need to synch private keys, which is a security nightmare.
With Telegram I do not have to worry about losing my "primary" device in order to access my account. Telegram is more a social network than a chat app. Moreover Telegram does not require me to feed it my whole Contact List in order to communicate. WhatsApp has this limitation on purpose (there actually are workarounds but they are "hacks" and not how Meta wants you to use the app). It is very suspicious: why can't I search for a WhatsApp contact by manually typing in a number into WhatsApp? Instead I need to put it inside my Contact App and grant WhatsApp full access to it. LOL
Matrix has been doing that for years