> databases also solve this problem

They could, but are typically configured not to.

With default settings they let other processes' commits cut into the middle of your read. (See READ_COMMITTED.). I was flabbergasted when I read this.

When you turn MSSQL up to a higher consistency level you can get it to grind to a halt and throw Deadlock exceptions on toy code. (Moving money between accounts will do it).

I used to advertise STM as like ACID-databases for shared-memory systems, but I guess it's even more consistent than that.

Postgres's `set transaction isolation level serializable` doesn't result in deadlocks (unless you explicitly grab locks) but does require your application to retry transactions that fail due to a conflict.