Speaker height vs ceiling height

Take a joke.
Having said that there are tall speakers that beam in narrow fashion like a Electrostat so there is no easy answer. There is a huge difference in how a Planar, Electrostat and a Dynamic behaves.

Height is not nearly as big of factor as length and width are. For someone to say you could not put a 6ft speaker in a 7ft tall room is making a way to blanket statement. IMO.

Vertical dispersion in lines planars and stats work often in lower rooms. From what my ears say atleast.

I happen to own VMPS FF3 SRE speakers in a drop ceilng basemant and at 68in tall with the ribbon mids they work great in my 14x24 room.