When a Harvard dropout writes a small system in PHP, and needs to call in the big guns to try to unfuck the situation [1], who should he call? Someone who got really good at jQuery at university?
Besides, aren't modern mainstream languages bragging about having nothing to learn? Learn go in just a couple of days, etc.?
[1] https://engineering.fb.com/2014/03/20/developer-tools/hack-a...
Anyone who learns Racket will have learned ways of deconstructing problems that will make them far superior in problem solving to those who learn only e.g. Java and only know how to do things the OO™ way.
At this point, nearly all the code I write is in JScript, Pl/SQL, Python, and T-SQL. I learned none of these while in school: Javascript was not yet invented when I was getting the degree.
I will say that SNOBOL, of all odd languages, was useful to me after school in learning Perl.