- reduces the number of TCP connections - reduced the risk of failure if the relevant edge node can't be reached
Browsers don't support cross-site caching of 3rd-party content so whatever limited benefits there might have been of using a library CDN are long gone
It's about getting jquery physically closer to your users. And sure upload it to your "own" CDN that you pay Azure or whoever for.
I be willing to bet that most web developers don't know about how the browser cache is partitioned
And most people don't know that it never really worked (apart from perhaps a few Google fonts)
- reduces the number of TCP connections - reduced the risk of failure if the relevant edge node can't be reached
Browsers don't support cross-site caching of 3rd-party content so whatever limited benefits there might have been of using a library CDN are long gone