Overnight they binned the free model and required an extortionately priced premium service to maintain the ability to embed images on external sites like this. It destroyed countless build threads on countless forums overnight.
I did self host things for a while - right up to the point where completely at random a Russian car forum hotlinked to an image I had used in a thread somewhere, and the resulting traffic basically just saturated my internet connection as it was getting downloaded many thousands of times an hour. Less of an issue now as the server itself would be the limiting factor...but it's an experience which has always made me wary.
ImgBB offer a free and paid service, and I've used the paid version for a couple of years now as it's only a few quid a month and it's a service I make a lot of use of.
It's very like Photobucket to use, drag and drop uploading and then it just gives you a selection of links to copy and paste into posts.
I know quite a few folks use Imgur for this purpose, however if you actually read their acceptable use policy they specifically state that their service should not be used as your content delivery provider, rather that they see themselves as a standalone gallery, more like Flickr. Which I know you in theory can embed images from but I've never managed to make it work!