The biggest problem I have with Kobo isn't even really something that's their fault or that they can do anything about. Amazon through their Amazon Unlimited program has locked a bunch of major authors into exclusivity contracts where they're contractually barred from distributing their ebooks on other platforms. That in turn means a bunch of major authors are just completely unavailable anywhere but Amazon, and of course Amazon ebooks exclusively only work on Kindle devices. It's a vicious feedback loop where authors refuse to leave Amazon because it's the market dominator by a large margin and consumers refuse to use anything else because all the authors are only on Amazon.

If you can make do with non-Amazon sources of ebooks it's great to do so and we really need more people doing exactly that in order to convince authors that the Amazon shackles aren't worth it, but it's definitely a struggle sometimes.