Jr devs have the tendency then to discard jquery because "is old" not because it isn't working anymore.
That said, front-end frameworks can of course be a better choice for many things, even if it's just because it provides this kind of organisation by default making it easier for the, ehm, less organized devs.
Unless of course I need to support legacy browsers, then jQ is a no-brainer - that crap is solved there and I don't want to have to deal with it myself.
And while jQ is large compared to my little home-grown set of wrappers, it is small compared to all the other stuff many pages draw in these days, so perhaps size isn't a great metric to criticise it on!
Companies are getting more security-conscious because of all the hacks and the pain of keeping old browser support is no longer outweighing the risks of upgrading is my theory.