What Mostapha said.
If the HB Validate Model component or the PO_ValidateModel command is telling you the Model is valid, then you can assume that’s the case. So you don’t need Rooms for a valid model.
Granted, a Model without Rooms is not simulate-able in EnergyPlus and there can sometimes be advantages to setting up your Daylight simulation model with Rooms. Notably, making sure that all of your Rooms are closed volumes will prevent light leaks in the Radiance simulation. Also, using Rooms of closed solids essentially absolves you from having to check the normal direction of Faces to make sure that they’re correctly assigned as Floor/Ceiling (and are getting the correct corresponding reflectance for floor vs. ceiling). This is because Honeybee Faces of closed Rooms always point outwards from the Room volume, enabling the default assignment of Floor v. Ceiling by normal direction to always be correct.
But there’s no hard in fast rule that you need the Rooms to make the Model valid or to be able to run Radiance simulations with it. So there are many cases where it’s just preferable to take the “orphaned” geometry (that is, the Shades, Apertures and Faces without a parent Room) as they are.
We even have some future Radiance workflows planned that are optimized towards this “orphaned” workflow where you can represent detailed Radiance geometry with Meshes instead of individual planar units. You’ll know when these are being implemented when you see this issue close: