Randomly asking users for their phone numbers should not be a thing
I contacted Twitch support about this and they told me to leave my feedback here. So here it is.
Randomly asking users who have never caused any trouble on Twitch to verify their phone number to keep participating in communities is not a nice move. In fact, I'd call it an a-hole move. This does absolutely NOTHING to keep chat safe.
Ask people who are banned in multiple chats for their numbers, I don't care, at least then you have a proper reason. What Twitch is doing right now, however, -- and it's affecting not just me but a significant number of people as the topic is frequently mentioned here and on Reddit -- is scummy.

-
ulumuluorc commented
I also contacted Twitch support because I didn't get a message:
First I thought I did something bad and got banned.I can't activate because I don't have a cell phone.
Sorry to all the streamers in my list. I have been watching for 1 year.
I won't be able to use Twitch anymore.Bye bye :```((((``
-
dirtyjester1 commented
I can confirm I am also affected by this same bug.