their “selling” point
Here's one place to begin. They're not selling it, it's literally free. Speaking for myself but I just cannot bring myself to criticize a free product which is not a monopoly. And this clearly isn't a monopoly. It just feels entitled.
Amazon ads
The tiny flaw in the above logic. Reminiscent of similar scandalettes involving Mozilla. But these sponsorship deals have always been easy to disable, even before they get dropped like a hot potato because of the backlash. I always come back to the same thought: how much are we actually paying for this product that is apparently valuable because we're using it and concerned about its flaws? We're paying nothing.
Or tell me with a serious face how the snap thing makes the life easier of someone wanting to install a deb.
The typical Ubuntu user will not know what a deb is, and should not be expected to. That's the point. It's meant to be easy. Whatever else they are, Snaps are definitely easy.