I think it's just a way of saying, "don't want to work on that, I am a (something) developer only". Eventually it goes all the way up and down the stack. I am from the era of "full stack" being called out as a specialty, capable of any language or concept in the stack, but maybe it's not a word anymore.. 😂

I can understand, when code is passion, and consuming your soul, most can only do it on the same project for 2 years, and then they either go to another project(I recommend this), or they continue at the current project with a bunch of reasons and meetings about why things don't need to happen.