> Only PCREs are exponential time, in service of a feature you basically never need. Regexes are always linear time.

Any re dialect which supports backtracking necessarily has a non-linear worst case, and while a select few have very high resilience against exponential backtracking (e.g. never managed to make postgres fall over) most can be made to fail with a pattern a few characters long.

FA-based engines are getting more popular, but they’re far from universal.