On the "quote tweet" debate:

QT is one of several decisions that made Twitter into a place where powerful or 'influential' people post, and most of the other posts are reactions to that material – agreement, dunks, critiques, jokes, etc.

Even if people didn't always use it for that themselves, it was part of creating the overall feeling that there is one big topic under discussion at any given time – and so of course you add your opinion on that topic.

Not having QT also encourages replies!