There are many common options like Slack, IRC, Keybase, and others. The hardest choice is finding a technology folks can agree upon; convenience and inertia go a long way towards maintaining a successful chatroom.
(Oh I didn't even mention the bridges to other platforms like gitter, irc, slack, etc. that matrix contributors develop...I honestly don't know why matrix has not crushed every other chat platform yet.)
EDIT: To clarify, matrix-based platforms like riot.im are chat platforms not really what most might call "traditional social media/networks".
Texting and other chat applications are instant.
Email used to be a more instantaneous thing, but it has evolved into something that many people want to take a break from, so sending an email might mean that the recipient doesn't see it for hours or days.
I’m trying really hard to get people to use email again for questions that they need answered but not immediately. But I seem to be losing that battle.
The "bigness" of an email come from the most usual workflows in mail programs: to respond you have to go through 2-3 clicks first, you usually have to wait some small time for sending them, the contents are usually bigger, there are quotations automatically added, there are signatures, there are more buttons and fields and options in the window - the whole thing is just more massive.
there is a' delta chat app that uses email as 'backend' and it works quite well)
That's true, but the vast majority of users misuse email and the vast majority of clients do not bother with properly threading it. So conversations become very cumbersome.
On usenet, it was easy to have threads that were hundreds of posts long with multiple conversations going on, and pretty easy to jump into one of the subthreads to post a response. Email could be the same way, but not with the way things are today.