I actually have an avo tree taller than me that I started this way 10 or so years ago. It is in a pot, and our climate is a bit cold for them, so I move it into the house in winter.
These are normally outside, just hiding from the worst of the winter.
I wouldn’t consider your statement wrong, but maybe just a tad bit too pessimistic. I don’t know the numbers, my point was more on the matter that - based on my readings - the chances of getting decent fruit are not too bad.
Like another commenter said: worst case you can graft a good variety onto your seedling so that you’ll get good fruit no matter your luck.