Yeah, tbh I find the "Timebase Time, but MIDI items don't obey" thing also "not quite right somehow".
But as there's been various discussions about it already (e.g.
https://forum.cockos.com/showthread.php?t=81012), and schwa explained the rationale behind it I just take it as a given...
Btw. you
can make time-based MIDI items it's just not very obvious:
Item Properties -> Properties... -> enable "Ignore project tempo..."
There's also an
SWS action to do it in bulk:
"SWS/BR: Enable "Ignore project tempo" for selected MIDI items preserving time position of MIDI events (use tempo at item's start)"