That statement is true and explains why we should support replacing FPTP, but doesn’t mean you shouldn’t vote tactically. Hating the system is reasonable, but playing the system is necessary whilst it’s in place. Otherwise you’re just weakening support for replacing it.
Note that I don’t mean tactical voting is always the best option, just that it’s not a tool you should discard entirely, at some point your tactical vote could get FPTP replaced, so don’t be too uncompromising.