I downloaded a neat little low-poly model from Sketchfab to have a look at the geometry and organisation of the scene:
Low Poly Isometric Rooms by Brynn on Sketchfab
I was expecting all the surfaces to be flat colour materials, no textures involved, but I discovered that every material is actually using the same texture, which is a palette of different colours. They’re all UV mapped to use small sections of the colour palette and produce the single-colour materials.
So my question - is that a deliberate choice by the artist? Is it because different programs handle materials/textures in different ways? Is it something to do with Sketchfab or the FBX format?