Controlling node consensus is the most important "layer". Nodes enforce protocol rules. If most "dapps" are using Infura, then Infura can easily force changes u

Controlling node consensus is the most important "layer". Nodes enforce protocol rules. If most "dapps" are using Infura, then Infura can easily force changes upon not only the dapps themselves but the entire network. Ethereum's engineering decisions have absolutely led to this, as well. Arbitrary "dapps" do not need a blockchain. Having all of this unnecessary data "on the blockchain" makes it bloated and impossible to validate, leading to entities like Infura.