What's wrong with comparing strings in constant time?

Question

Burglary protection

From the PHP documentation:

Note that if you are using the crypt() function to verify a password, then you need to guard against timing attacks by using string comparisons that take constant time. Neither the PHP == and === operators, nor the strcmp() function are. The password_verify() function does exactly what it needs to.

What's wrong with string comparison that takes constant time? password_verify() apparently makes it longer, preventing the enumeration, but why such a strange wording, it would be written that it works too fast, therefore, it does not fit.