There’s a microchip in my toothbrush. But WHY?

I have this exact model of toothbrush; I always assumed that it was for something like this, because a light popped up when I was using the same brush head for a while and went away when I replaced it without me having to do any resetting.

It's not doing wacky lockout nonsense (the motor still runs after it tells you the bristles are worn out and will turn on even without a head attached!) and it's not like it can log the data anywhere so I'm fine with it.

Another reason for me to continue buying $1 five-packs of non-electronic toothbrushes!