so closed source wallets are also cool because they are on an open protocol?
do you know what point you are making?

when you stream sats from fountain you are simply directing the bank to send them. they check your balance, take their transaction fee and send the sats from wherever.
they could do exactly the same thing except FOSS. but they want to leverage state violence to protect their business.

FOSS is important because it protects users and encourages the free development of ideas. among other reasons.

off the top of my head I can't think of any closed source software I have installed anywhere.