WHY doesn't Python's Ursina module load textures from .mtl file?

Question

Why doesn't the Ursina module directly load all textures from an obj's mtl file?

Let's assume I have 4 files:

test.py:

from ursina import *
app = Ursina()
e = Entity(model="test.obj")
EditorCamera()
app.run()

test.obj:

mtllib test.mtl
o Plane
v -1 0 1
v 1 0 1
v -1 0 -1
v 1 0 -1
vt 0 0
vt 1 0
vt 1 1
vt 0 1
vn 0 1 0
usemtl test
s off
f 1/1/1 2/2/1 4/3/1 3/4/1

test.mtl:

newmtl test
Kd 1 1 1
map_Kd texture.png

texture.png:

If I run the .obj file in a 3D viewer, it loads the texture, but WHY doesn't Ursina do the same but just ignores all map_* and refl commands in the mtl file?

I want to know WHY Ursina ignores those texture commands, not how to fix it.