The Amiga was doomed by being a '90s machine born in the '80s and (mis)managed by a company that operated like it was the '70s.
It's true that the only commodore subsidiary that knew what to do with it was commodore uk.
However the problem goes back further than that. It was supposed to be a games machine, but they were really designing a computer. Which seemed to work out better after the video game crash, but it meant that the all things to all people idea started before commodore even knew about the amiga.
ECS just wasn't good enough, AGA was too late. But they were competing with computers that could have a new graphics or sound card added without alienating your entire userbase and they weren't cheap enough to compete with consoles.