I would always encourage using a library over not using one - if you're not using a library you're just going to end up making your own anyway to "save time" - might as well start with something everyone already knows. If your project is also going to be something that a lot of people touch, you don't want to be using your own solution or a lesser known solution just because it's neater - that would be a waste of time.

So yeah, in my opinion if you opt to use your own solution or a lesser known one, I'd say you're at least a bit of an asshole because 1.) you're assuming you know better than the majority of people (who don't have a problem with using jQuery) or 2.) you're wasting everyone's time by forcing them to learn something new when there's a perfectly fine solution already available.

They wouldn't remove it even if they had the choice, because recreating what jQuery does with regards to cross-browser compatibility is just wasting everyones time. I'm not saying it has to be jQuery, but since everyone is already familiar with jQuery and it works well - why not jQuery? Eventually yes I think we can drop jQuery in favour of native implementations, but most sites can't afford to lose that compatibility yet.

I disagree. AngularJS uses jqlite underneath for lots of stuff it does with the DOM. It can use jQuery if it's included, and if you create your own directives, jQuery is a great tool. No, you shouldn't create a single page app based on bare jQuery. Yes, you should use jQuery for manipulating the DOM vs the native DOM manipulation functions.