If you stream on twitch, midroll ads make it more difficult to built your stream and hurt your income that would otherwise be from subs, donos, bits, whatever bs twitch is doing. Preroll is better.
You can stream however you want but I've absolutely ducked on some streams I'd otherwise love to watch because of midroll ads. Streaming is about being able to engage, or just otherwise have a conversation with chat and an ad stuffing itself in the middle of a convo just ruins that vibe real bad.
They make twitch money tho, which is why they push for them so hard.
I assume if you have this turned on, you've been having some serious issues with harassment on twitch. That's fine, twitch does not give a fuck and they do not make it hard to just smurf accounts all day to pester people, really. There's a couple of tools nowadays to help mitigate that slightly but at the end of the day the site will never staff anywhere near enough people to actually be able to handle problems like that correctly. That only leaves you with hamfisted, collateral damage options like this. That sucks, and I am sorry you have to deal with all that.
But there's no reason twitch needs my fucking phone number. I don't trust any company to use a phone number for verification and not use it for ad profiling. This has also kept me out of a few channels I'd otherwise enjoy chatting in. Per the above, at least that's a fair and understandable reason from the streamer's POV. "Sorry, I have to have this bad setting on to make streaming tolerable". They shouldn't have to make that decision, but it's not a wrong one to make given the circumstances.
You can replace twitch with discord for all of the above too, they have the same option available. We've got plenty of discord complaining here already.