Gosh people are being touchy about duvets aren't they. Like they are a new invention.... the Chinese had them in 3000 BC! en.wikipedia.org/wiki/Duvet#:~:text=Records%20show%20the%20earliest%20duvets,though%20not%20by%20their%20courtiers.
I am disabled, and they are a bloody miracle in my book. For all those who think that putting a cover on a duvet on your own is easy-peasy, perhaps they should try it when they can't stand up for more than a few seconds without falling over when you can't also grip walking sticks with the two other hands that you don't have.
I got mine off Amazon a few years ago, and I can't even recall the brand now. They wash and dry very easily, and I have a thin quilted cover over the top (which no, doesn't slip off). This also means that I can vary the amount of bedding very quickly - just whip the quilt or the duvet off depending on the ambient temperature, so no faffing with weights and combinations.
Like anything else, different things suit different people. I wouldn't be without mine and highly recommend it. It may not be for everyone. But then I don't like chocolate, but I don't find any need to have a go at people who like it.