Just for example, if a potential employer running a PHP/MySQL shop could easily look up my opinion of their chosen tools, most would only hire me as a last reso

Just for example, if a potential employer running a PHP/MySQL shop could easily look up my opinion of their chosen tools, most would only hire me as a last resort if at all. Those tools are still popular enough that I would never bet my career on being able to avoid them indefinitely. (I'm more candid with my current manager now that we trust each other, in fact his views are stronger than mine.) And that's without even getting into political views like IP law, or whatever the hell future landlords or neighbors might object to....