[throwawayboise]

The downside of "good ol' locking" is that you can end up with more fights and possibly deadlocks over who gets access and who has to wait.

With Postgres/Oracle MVCC model, readers don't block writers and writers don't block readers.

It's true that an awareness of the data concurrency model, whatever it is, is essential for developers to be able to write transactions that work as they intended.

[lifepillar]

It’s not that conflicts magically disappear if you use MVCC. In some cases, PostgreSQL has to rollback transactions whereas a 2PL-based system would schedule the same transactions just fine. Often, those failures are reported ad “serialization errors”, but the practical result is the same as if a deadlock had occurred. And Postgres deadlocks as well.