It's for voice, so that your mic is only active when you press an activation button. It's how most PC games do it, and I would say it's how most folks on PC use voice. It's honestly a pretty basic feature, and super frustrating that it seems not to be a priority.

Not joining the rooms Element suggests on its own client? Element will show you a list of suggested, popular rooms to join, and a fuckton of these are overrun by spammers and worse. If Matrix has basically zero ability to curate these rooms outside of "here's what's got the most members", then it absolutely should not in any capacity be recommending them, let alone as a way to get started for new users. It's fucking ridiculous, and before you say "Well why should they be expected to curate the rooms they suggest?", imagine the fucking disaster Discord would have on its hands if it started recommending servers, and several of its top 100 claimed to be related to popular FOSS applications but were actually completely unmoderated and filled with CSAM and Bitcoin scams.

just this week I've had multiple random matrix accounts start a chat with me to post an Imgur link with some Hitler bs. I assume they just chose random members of one or more fediverse related public matrix rooms to send that to. they probably just do this with random public rooms and the fediverse relation didn't matter.

Decentralization actually can be really powerful to give you a backup even if you prefer Signal; Signal's servers very infrequently go down, but when they do, you entirely lose that channel for an unpredictable amount of time.

You can't know with certainty on Signal that the client and the server are actually keeping your messages encrypted at rest, you have to trust them.

With Matrix, if you self host, you are the one in control.