[AlisdairO]

I think it because a significant fraction of my career has been spent fixing db-concurrency-related mistakes for people once they hit scale :-).

I’m not talking about using cascade - this applies perfectly well to use of on delete restrict. FKs are more or less the only standard way to reliably keep relationships between tables correct without raising up the isolation level (at least, in most dbs) or doing explicit locking schemes that would be slower than the implicit locking that foreign keys perform.