Bank managers have very little understanding on the technical functioning of bitcoin and where this technology is heading. The fact that they didn’t invest in Blockstream only demonstrate that (thank God). Very few have hedge their bets with some bitcoin comapny but no more. Of course they have little interest of deeper understanding because we all know this technology can render their very lucrative business model into an almost obsolete one. However, keeping small blocks is a great way to push users into potential proprietary off-chain systems controlled by banks which can be used for fractional reserve, cooking books and all the great things they love doing. On the other hand allowing people to directly use the blockchain is a bigger threat to their business model.