Where is the trust then ? Why would that very cartel do sth 'bad' ? Could that 'hide' ?
As a simple example. Then Bitmain/Jihan Wu and the mining cartel will have a better probability to, increase the block size/remove the limit, remove the Core developers, even if if the users/community do not want both.
Plus if no one ran full nodes, you want the users to trust the miners?
You just must trust HONEST miners - as described in the initial financial term sheet of Bitcoin - read the White Paper - that is binding, only.
WHO ARE THE HONEST MINERS? Bitcoin is robust because it was designed to assume that EVERYONE can become a BAD ACTOR against the network.