If pays attention to the direction of the de-dollarization concept, it refers to reducing dependence on the US dollar as the dominant currency in international trade and finance. Russia and India have previously expressed interest in increasing trade in their local currencies to reduce dependence on the US dollar, but these efforts have faced challenges. One such challenge is the limited acceptance of this currency in international trade and finance. Yes, it's very likely that Dedollarization failed before it even started as you mentioned.
It's not limitied acceptance because these BRICS countries have ironed out all the details for their plans so I do believe that this is not the case of acceptance, I think that it's the case that they're still trading with other countries with dollars and they probably don't have enough dollar for their trades with the other countries. Not to mention, that the hold of dollar in the international market is so strong and deep, they need a lot of countries to completely abandon the dollar for international trade before they can make any difference. Don't get me started with politics too, that's another matter that has a big influence why this dedollarization isn't working as intended.