For sure there is a reason behind. It's just not a user-focused reason but a business one instead. One guess would be that the browser is a environment the user can kind of control, so they can block tracking and so on. When you're using the app, you don't have the same control anymore, so the business can receive more metrics from people that they wouldn't before.
Not saying this is good/bad, just that there is most probably a reason behind the choices they make.
Bootstrapping is pain, but at least you and your customers retain control long term.
Someone in the twitter thread says it still works on firefox for android, which means it's really only broken on chrome. Chrome doesn't have adblock, so it's not like this move results in less of their telemetry getting blocked.
How could it not be bad to impose these restrictions for anyone other than the company? You can use the app if you want.
There is a seemingly persistent bug where reddit fails to remember preferences surrounding mobile/desktop and old/redesign. Sometimes you will click a link and the page it delivers you to will be on the mobile site, sometimes it will take you to the redesign. It's been going on for at least a year. I use reddit a lot and I run into it at least every week. Sometimes it sticks and I have to relog to get my preferences back.
Firefox for Android prevents such attempts by default. That, plus uBlock Origin with its integrated element picker to permanently block elements make reddit bearable.