Follow rest for small diameter shafts

I've only ever seen steady rests with brass wear surfaces. The brass basically just gets annihilated every time you use the thing, sending crud everywhere. Why don't they use UHMW or PTFE like in the video? Low friction, self-lubricating, won't contaminate your part, easy and cheap to replace. Makes all kinds of sense to me.

I mean, I know that's not the point of the video. The video is why that style is bad. But still the plastic wear surfaces seems like an improvement.

Follow rest for small diameter shafts - video