Blocksize should be growing at the same rate that bandwidth availability is growing, but is isnt. Why not? That wouldnt affect decentralization at all.
Secondly, the Chinese miners overwhelmingly support segwit2x, including the 2mb HF that comes with it. If they are trying to keep asicboost (which has not been proven to actually being used), why would they support segwit2x instead of trying to force BU instead? Segwit2x includes....you guessed it....segwit...which disables covert asicboost.