I'm speaking to the jquery example. 99% of howtos have instructed people to pull from CDN because everybody (probably) already has it. It has been conventional

I'm speaking to the jquery example. 99% of howtos have instructed people to pull from CDN because everybody (probably) already has it. It has been conventional wisdom for a long, long time. I just checked, and googling "jquery cdn faster" brings up plenty of examples.