It has good margins and could afford to market heavily and invest in feature development vs anything else. As a result an alternative might well be great for users, great for the world, and also an unsuccessful business.

Doubly so because it's essentially already solved. Setup a standard NVR and portmap it. The marginal gains are just in making it more secure (few care, obviously, or ring wouldn't exit) or a little easier to configure.

I'm not sure how meaningful that actually is. I know that it's reasonably easy because I've done it a number of times, but I have zero interest in making a productized solution.