I don't actually think the lack of choices is the real problem though. The issue I see is that things like AdSense or AWS are able to financially prop up Google

I don't actually think the lack of choices is the real problem though. The issue I see is that things like AdSense or AWS are able to financially prop up Google and Amazon's ventures into a myriad of other markets that make them immune to the actual market forces in those domains. It ends up having a really bad distorting effect on any of the other players trying to run a normal business.