Re: This whole debacle mirrors Gamergate
Well not really much. Developers will get the dependencies as they work (using bower or whatever the JS dep manager tool of the week is), and then build a single JS file at deployment time (using webblywobblify or the JS build tool of the week), and that goes up to the server for production. I doubt anyone has every done <script src="http://randomsite.com/pad-left.js">
I'd only ever load something from a non-local site if it was something I regard as stable, popular, and coming from a robust CDN.