To my understanding (please take with several grains of salt), some folks felt like it would encourage toxicity since you can essentially mock something someone said without saying it to them directly, while sending your audience to the original post, and I believe for quite some time the plan was intentionally not to add it

On the other hand, I’ve heard folks suggest that by allowing people to have their own isolated conversation about an idea you can potentially limit some of the harmful consequences of people with large audiences or something, but I don’t remember the exact explanation

Personally I’m happy to get quote posts and I’m happy that mastodon is cautious about implementing features that facilitate hostile interactions in the way that major platforms do for engagement

Hopefully someone can chime in with a more informed/detailed explanation, but I thought I’d share what I know in case I’m the only one to reply :)