It would be a pointless number if each satoshi is equivalent to 1 USD and it isn't so your point is invalid. A supply cap like the 21 million bitcoin has something to do with scarcity, because if they can't add more into the supply, the lowering of it will only make the price increase which is scarcity.
Most people don't understand how division can increase supply.
Here it is.
if Bitcoin can only be divided by 1,
then
21 million BTC / 1= 21 Million BTC tradable supply, which you could claim scarce
but the problem is the division is not limited
21 million BTC /
.5 = 42 Million BTC tradable supply
21 million BTC /
.25 = 84 Million BTC tradable supply
Now lets look at a satoshi 8 places to the right of the decimal
21 million BTC /
.00000001 = 2.1 Quadrillion BTC tradable supply
Now while the number on the left did not change, the total Tradable Supply increases dramatically.
Exchanges have 9 places to the right of the decimal for some trading pairs.
Lightning Network has proposed 12 places to the right of the decimal.
They can inflate the tradable supply units to an unlimited number all the while claiming bitcoin is scarce because the number on the left won't change, but their ever increasing division number is changing so it is increasing the supply, but they think you are all too stupid to figure it out.
And for the few that brought into the nonsense that division can't increase supply, I suggest you get out an old biology book,
https://en.wikipedia.org/wiki/Cell_divisionCell division is the process by which a parent cell divides into two or more daughter cells.