That is sort of my point. I think "repeatable read" is a fools gold. You think you wont need to do locking, but it is too easy to make incorrect assumptions about what guarantees "repeatable read" provides and you can make very subtle mistakes which leads to rare, extremely hard to diagnose correctness issues.

Repeatable read type of setups also make it much easier to accidentally create much longer running transactions, and long running transactions/too many concurrent open transactions/etc can create really unexpected, very hard to resolve performance issues in the long run for any database.