I think the automatic answer people have for big corporation - to have more data is usually false. I think they don't care about your data that much. And generally they respect it. They mostly need data to target ads and they have it already.

I think in case of regulations like this, it would be harder for small players to participate in the market, and thus they would prefer to use Facebook or Instagram instead of opening a website or their own system. The same with cookies alerts, GDPR, DMA, etc. It is not a problem for a large player to implement it, but now creating a fully legal website processing data becomes quite expensive and it is easier to just use a platform provided by a large player.