Really, you've always had to be careful with MySQL. It really was the PHP of RDBMSs.

The silent "SHOW WARNINGS" system, nonsense dates like Feb 31, implicit type conversions like converting strings to 0s, non-deterministic group by enabled by default, index corruption, etc.

Not just constraints, transactions were also a no-op. The MyISAM engine is still available in modern versions if you want to experience this, it's just not default anymore.

I love Postgres in 2026, but it really was not a viable enterprise option before 2010. MySQL had decent binlog replication starting in 2000 which made up for a lot of the horrible warts it had.