Mastodon already have like 3 too many timelines, and CalcKey adds another couple.
Name tags are bizarrely massive, dwarfing toot text.
Visual linking of long threads is thoughtful, and nice to look at, but doesn't help to see who talks to whom. Again, Mastodon is bad but this doesn't help.
Quote tweets are done in proprietary way, not compatible with QTs outside of CalcKey.