It really is a lot more practical. Most webapp devs using SQL databases spend a bunch of time engineering some notional failover into their app that's completely undermined by using a non-HA datastore, a bunch more time mapping data to and from square tables where it doesn't really fit, and end up with a system that's still last-write-wins at the user-facing level. And the ones where it isn't aren't because they used those SQL transactions, but because they wrote their own versioning layer on top.