jQuery promotes bad development patterns, AND brings a cost for end users. Developers will do themselves and futures devs a favor by not choosing to use it. Is it really gatekeeping to expect people to be aware of commonly used 10 year old features?
I assume developers who share YMNNJQ are just sick of inheriting messy projects built with jQuery. I know I am.
Part of my screening process is making sure something like that doesn't fall in my lap again. Even static sites aren't safe these days.
If you do web development as a job, it's your responsibility to stay up to date on what best practices are. With EC2015 being several years ago now, jQuery wouldn't be a learner's starting point today.
Those that developed bad habits during jQuery's heyday a decade ago may still be writing bad code. And it's someone else's job to clean that up. That's the circle of life, and it's hardly exclusive to jQuery users.