The regulatory architecture of "big tech" is an unmitigated disaster.
You can't have two entities effectively control every touching point with the digital domain for a major fraction of the planet.
There is absolutely no reason to trust that they will not abuse this position in opaque and impossible to trace ways. These are trillion-dollar powered for-profit entities, with armies of lawyers and lobbyists that can intimidate medium sized countries. They will exploit every weakness of incompetent, confused and captured regulatory/political systems. Because that's what they are legally obliged to do for their shareholders. And these shareholders care zilch if this duopolistic - fingers in all honeypots - design undermines our entire digital future. They just want some tech "winners" in their portfolios.
The longer nothing serious is done the harder it becomes to do anything.