Hm, perhaps they think you can fiddle around more with the lighting and textures in Blender, or that the render engine is better. I'm taking wild guesses here as I've never used tiltbrush, and only really seen a handful of people's creations with it XD
Nodes look like
This is a super basic one. Starting from the left, the first node checks for where a ray hits a hair strand, this feeds into the factor of the colorramp node which tells the hair to start from black and grade up to red at a certain point. It then feeds into the base colour of the other two nodes which control shininess and stuff (I had to use two separate outputs because at the time I made this Eevee couldn't read the principled hair bsdf node and I needed my test renders in Eevee to look at least recognisable, you generally only need one), then the lot is combined into the output which is what gets rendered.
Above node tree results in the hair (mohawk looking thing down the centre in this case) being black with red tips:
Solid white possibly means the material wasn't imported at all, you might need to check if a uv map and the textures exported and then reapply them.
