You can see why Amazon's efforts suck just by using it. That isn't to say I defend Steam, or Epic, or GOG, or UPlay, or Origin, or Battle.net, or Microsoft Store because they all suck. They suck for existing as separate things that all do the same thing but each eating 500Mb of space on my computer.
The ideal situation would be a federated platform where everyone shares a single sign on, everyone shares the same update, backup & restore mechanisms, everyone can join the same lobbies and matchmaking. But that's too sensible.