Think of it like the difference between renting and owning something. When you rent a home, you do not own it. You don't get to choose. Want a nicer water heater? Not your choice. The owner takes 100% of the responsibility, but often isn't penalized for misbehavior. So they can for instance, decide that they don't like you, and you no longer can use their servers. Or perhaps they dislike other companies, and strip features from the rental agreement. Even worse, all your valuable data, along with everyone else's, is all stored in a single valuable location, becoming a prime target for thieves. I half expect some of the "data breaches" we see are inside jobs, where the company leaves a loophole open, tells the "thieves" about it for a small sum of cash.

I personally like self hosting. Once you get into it, and understand how to reverse proxy, and set up a domain, you can essentially self host anything ridiculously easily. Like, for me, setting up a container, and funneling it into my reverse proxy maybe takes like 30-60 minutes, ironing out bugs and stuff? Sometimes if it's particularly easy, it takes like 5 minutes lol.