all the jets/float hinge are brass anyway?
Yes that is true.
That is why when you see carbs with all brass floats many of them have extensive corrosion. Honda went to the plastic floats to keep the weight down.
But ethanol fuels are new to the game and the moisture absorbing properties of the ethanol fuel do not help as far as the corrosion.
On my 1969 Honda CB750 carbs the screws for the vacuum ports were aluminum.
The mixture screws were steel NOT brass. Aluminum has less corrosion potential with steel than with brass.
As the production increased, the brass was was easier to machine than steel.
But the bass pin in the float and the float tab is brass. That is good because those parts are subject to dry and wet cycles. Steel would have corroded badly like those steel spring clips that held some of the jets on some models.