Yeah, I don't think most people object to Ring video potentially being used by LE (I'm sure there are some though). I think the biggest complaint is the complete lack of due process and even the lack of notifying anyone when their footage is used.
No. The article is about a failure of that exact system. Judges just sign search warrants for just about anything; the only thing they check for generally is that it's not involving the search of hundreds of people. Invading the privacy of 1-10 innocents is just a rubber stamp.
Yes, but obtaining footage directly from 10 different people is ten times more work than obtaining the same footage from a single source. That additional work increases friction and decreases (but certainly doesn't eliminate) the level of abuse that will happen.