Avast sucks... no matter how you see it or when you see it years ago or today, it sucks and it will always suck. even if it didn't tell you about installing chrome it will still suck.
Especially when it looks like another adware installed on a computer. the question is, why are you using Avast? or why did it become "popular"?
I like how you say they mention "extensions = better", when the only extension people really care is Adblocker and you can pretty much get adguard or adfender or host block as an alternative to the extension while Microsoft adds the support to edge. if a person doesn't care about ads that means they think that's "normal" so don't think ads can be blocked.
I think Edge is good, I like it, it doesn't make me a sandwich but chrome or Firefox won't do that either. I still have Firefox portable for small reasons like when I used WhatsApp web or some video streams that don't go fullscreen when you press the button on Edge.
So, I never saw wrong the way Windows 10 change defaults work now like Firefox complained. and I don't see wrong for Microsoft to display a "Give Edge a shot" message on windows 10 previews when you try to change it.
At least now browsers won't sneak install themselves and be "default" without a person knowing.