But initially there was no choice or selection. Ethereum was chosen for low transaction fees so Storj would be able to do micropayments and bear the fees. And that is how payments were conducted. This is the original idea I am referring to.
And for the whitepaper:
While we intend for the STORJ token to be the primary
form of payment, in the future other alternate payment types could be implemented,
including Bitcoin, Ether, credit or debit card, ACH transfer
To me this sounds that there are no fundamental technical reasons not to use other forms of payment. In another post you have indicated that these are basically legal reasons preventing you from using other coins as payment.
As this whitepaper is dated back to 2018 that makes me wonder if these legal problems are being worked on since then as well and if there can be progress expected to give SNOs additional options to get paid by the coin of their choice.