Aint that funny thing.
They are BTC fundation. They promote BTC. But still they charge for membershin in dollars (you cna pay in BTC if you want). How funny is that?
For some time in the beginning, membership fees were a fix amount in BTC.
After a while, people started complaining that "no one could afford these fees".
There was a lengthy discussion within the Foundation about how this could be changed, with suggestions ranging from IIRC "peg it to GDP per capita" to the "Big Mac Index".
In the end, pegging it to USD was the most pragmatic solution. Period.
I fail to see anything funny in that.