Fetch API for ajax isn't in any version of IE or Safari, or any mobile browser apart from Chrome for Android.
And so on.
It's not so much that front end devs are lazy, but more a case that building a set of polyfills for each and every browser support problem is actually hard. "just use jQuery" gets around the problem. I think most developers want to write better code, but most projects don't have the development bandwidth for them to do things better.
Array.forEach doesn't work in IE8 or below.
Fetch API for ajax isn't in any version of IE or Safari, or any mobile browser apart from Chrome for Android.
And so on.
It's not so much that front end devs are lazy, but more a case that building a set of polyfills for each and every browser support problem is actually hard. "just use jQuery" gets around the problem. I think most developers want to write better code, but most projects don't have the development bandwidth for them to do things better.