I think this blunkiness is in part because these things are often created and designed exclusively by frontend and full stack developers. IMO systems like these need strong backend developer influence, with highly scalable data models and and as much work as possible pushed server-side.

In short, the system should be designed by people that despise the general state frontend development. It should still look good, I love a modern clean frontend (like Docmost for example), but not at the expense of snappiness and scalability.