You are not wrong, and the criticism is spot on. I think they have been too slack on beta invite as well as waiting too long to tune. They have started somewhat, but they better hurry. Every player are just as important here, and even if I say that I love the way Covenants are and how it works, it's not only me that needs to be catered to. I got guildies that takes performance above everything else, friends that wants to be as good as they can, I got guildies that see a transmog and that will be the reason for their choice and so on. Bit of nonsensical words from me here, but it's to make a point. I think Covenant are very cool, and the design is something I like too. But tuning it properly are just so damn important for the overall player base.
Like you say, you are sceptical, I think we all can be. We have seen blizzard use months into the live game to tune something properly. Legendaries, Corruptions, tier sets and most importantly, classes. They can't do that with this. I'll survive, but others might not.