As far as I'm aware most websites which appear to be decentralised, are only somewhat decentralised. pseudo-decentralised might be the word for it. As in, they allow contributions from the community, and largely there's no central figure, but ultimately someone controls it, and if they wanted could indeed intervene even if it hasn't as of yet.

Although, I'm not even aware of many websites that are decentralised. One could argue that the projects on Github are, and therefore Github is, but that's not entirely accurate either. Although, I agree, and it might even change my mind if I could be shown some websites which have actually successfully implemented it. Although, from my thoughts on it, it either can't be entirely or it'll be detrimental rather than beneficial.