Why does "tmux display-popup" block?

[Johannes Altmanninger]

Unlike for new-window and split-window, "tmux display-popup" blocks
until the popup is closed.

I wonder if there is a particular reason for this, maybe one wants
to run a script when a popup is closed?
But shouldn't this also be possible for split-window?

Maybe the blocking behavior is inherited from display-menu, without
a particular need?

This has caused some head-scratching in
https://github.com/mawww/kakoune/issues/5177

For that kind of usage, not blocking would make more sense.
Not sure how it's used elsewhere.