The fact a centralized system profits from engagement isn’t inherent to the fact it’s centralized, decentralized platforms are likely to do the same. As for your second point that their mistakes happen at scale, that is true. But also the things they do right happen at scale as well. All of the automated moderating and disinformation detection that has been in the works happens at scale too. It would be much harder to do similar in a decentralized system because of the partitioning of user data.