> Where before you had to trust one server, now you can have many. Multiple writers, multiple readers. That's all.
Those multiple writers, multiple readers are not free. They waste billions in server/electricity costs over traditional architecture designs. The most prominent blockchain bitcoin costs 2.5 billion dollars a year [0] to process a miniscule fraction of what Visa can handle.
YES, we know! If there truly isn't an alternative to PoW, yes then we are pretty much fucked. Quite a few more efficient alternatives are currently being tested (and I guess a lot more are to come), and it looks very promising.
Where before you had to trust one server, now you can have many. Multiple writers, multiple readers. That's all.
They are a drop-in replacement for having to trust admins.
On the other hand, backups and replicas could prevent other things, such as: https://www.youtube.com/watch?v=E1d5VvCa8Fo