There are only a few cases where that's true today. Probably 90% of the functions that helped a lot before have been implemented by browsers natively today.
I picked up jQuery because JS in browsers weren't cross-compatible for ages. I don't see a need to stop unless jQuery stops being cross-compatible.
So, it's not needed anymore. I also started using jQuery in order to get cross-browser support for handy stuff, but since that stuff is now cross-browser without using any 3rd party libraries at all, there is no need to use extra bandwidth and CPU cycles from your users to download something that basically already exists.
There are many reason not to use Jquery for greenfield projects now, but bandwith is not one of them.