That's like argueing that dictatorship might be better than democracy because at least there is someone to hold accountable.

Well, there is someone who is responsible, but the problem is that you cannot hold them accountable. Which is why democracy avoids the same concentration of power in the first place.

Which is also the whole point of decentralization. You avoid the concentration of power that would allow any single party or small minority to turn against you without any way out for you.

If you email provider starts selling your emails to the highest bidder, you don't need to regulate your email provider. You simply switch to a different one. Or run your own server. Decentralization is about keeping the power your hands.