I dont understand enough about economics to confidently argue about this. But it does seem laughable to me to expect BRICS to do anything cohesively.

China/Russia are not friends, they do not trust each other and even recently China was stealing land back from Russia. India is very much out for itself and has made a habit of fence sitting and flipping positions on a whim.

UAE are power brokers and not a mover and shaker on their own.

Most the rest of BRICS are powerless or fickle or too broken to reliably make changes or be relied upon if changes are instigated by the more senior members...

Cryptocurrencies are not going to change any of that.