Refugees from birdsite missing QT Quote Tweet might reflect on conscious design decisions made in Mastodon core, that could be modified in a specific instance. This means that if a poster REALLY wants QT, he or she has the option to move to an instance where that is supported.
Original 2018 Design Decision at https://blog.joinmastodon.org/2018/07/cage-the-mastodon/#design-decisions
Pointer from discussion thread from 2000 on Quote Toots https://github.com/mastodon/mastodon/issues/12753
Just because birdsite declares a unitary design approach doesn't mean that Mastodon developers haven't thought about a feature.
A fork of Mastodon is Fedibird, with features more like Twitter. https://github.com/fedibird/mastodon
The lead developer is @noellabo .
The Fedibird site looks to prefer Japanese writers. https://fedibird.com/explore
If anyone knows of English language Fedibird instances, perhaps we could help others to find them.