I use a 3rd party app maybe 1/4th of my time on reddit, so I could've technically gone without it. But I think anyone keeping up with the current situation can see old.reddit.com is on the chopping block soon, if not next. When reddit's admin team said half a year ago that the APIs aren't going anywhere for at least the next couple of years, and now have to deal with being called out on their deception, and even adding new lies onto the pile like the whole Apollo debacle, you know they can't be trusted in any capacity to keep promises.
If keeping an API accessible that does the exact same thing as their own app is too much of an expense to keep open, imagine how much maintaining a completely separate front end for their entire website must 'cost'. And that's in part why I've made this switch now and not when old.reddit.com gets killed eventually.