Absolutely. But for most common uses of backreferences, this is largely mitigated by having a post-regex step that compares capturing groups for equality, which

Absolutely. But for most common uses of backreferences, this is largely mitigated by having a post-regex step that compares capturing groups for equality, which induces overhead also linear in the length of the string. Of course this falls short of true backreference support, but for tasks where we do not expect potential matches to overlap, it gets the job done.