Decimal Places.
People start at the lowest and work up. Normal non-spam users would linger in the lowest levels. Why not.
What would happen if - just hypothetically - Bitcoin had 16 decimal places and not 8 ?
1 satoshini was 1*10-16 BTC.. transaction fee priced in satoshini / byte.
I think fees would come down, but not by as much as 8 decimal places.
Why not? The idea of adding more decimal / allow smaller fraction of Bitcoin has been suggested for years, even though most people would wait until Bitcoin price is very high.
But since it requires hard-fork, there are better & easier alternatives such as make default
minrelayfee on Bitcoin full-node client become 1 satoshi.