My perception is most developers who choose to use PHP these days for new development efforts either do so because it's their strongest language and do not want to reinvest the time to retool, or because of political reasons orthogonal to PHP's technical chops. Thankfully, it is still actively developed, so those who make that choice are able to take advantage of such new features.
I totally understand the choice to work in shops that have legacy php code: they have money and often times don't want to change off php. Handily enough, most of us like working for money.
What caused me to retool away from php was the fear that not enough new systems were being built in it, leaving a diminishing pool of jobs for a constant pool of developers not wanting to retool. I figured I'd give up my space to someone else, and seek my fortunes on other stacks. I don't think there is anything wrong with deciding X language will be the one you ride into the sunset on (some COBOL programmers I know make crazy money due to the economics of the ratio of jobs/developers). I just personally considered the risk of a job shortage to outweigh the rush of a talent shortage. (And I am so practiced at retooling, I could probably be ready to interview for a PHP job in a few weeks if I had to).
I think of choice of stacks from the agile way, "make it fast to change, and you'll be ready to snatch up arbitrage opportunities when they arise." Rather than the waterfall way, "pick the right tech that will last your career at the point of maximum ignorance".
I think most people mock PHP just because it's fashionable to do so, it's the "easy joke" that vb6 used to be. I wouldn't take it personally, you should own your choices.