i run my own shop. but i know what staff engineers/assistants do at commercial studios.
they show up early. set up for the session. do whatever needs doing as per the direction of the producer. then they tear down and go home.
everything's easier now vs. 30 years ago. not that much has changed technologically vs. 5 years ago. maybe plugins sound a little better, or there are a couple interesting developments like CLASP, but the real sea change was "before 2000" vs. "after 2000."
it's absolutely damaged the traditional commercial studio industry, yes. 2017 studio rates are often cheaper in absolute dollars (i.e. even before considering inflation) than 1990 studio rates. many major studios closed, others are living on borrowed time. whether it's damaged the music industry as a whole is a much more complex question.
depends on you, your needs, your goals, and the specific school in question. sometimes it's a good idea, other times not. and no, online resources can't replace good schooling.