This. Often companies that are in need of more bodies will hire people and tell them they can certainly help change the culture and help adopt a new language.

This. Often companies that are in need of more bodies will hire people and tell them they can certainly help change the culture and help adopt a new language. Everyone there wants to believe it but it'll probably never happen. There is probably a fun math problem here: count up the number of engineers, sum up their time in the language. If the average is X or more, they will never switch away from the language they've earned their keep in. It's too hard once you get past a point. Maybe that is already a rule. But I'm sure it is stronger for certain languages, probably PHP especially.