The reason is because the cartel needs to gradually consume the hashrate of the network, so it can delay the transactions of non-cartel customers who are on the blockchain. To force them to join the cartel or lose customers to the cartel.
Yes, much hand waving. Again, just because you can say it, does not make it so. There is zero evidence that a cartel of any size less than 51% of the total network can delay fee paying transactions issued by others to any noticible extent.
Your ignorance of Satoshi's white paper and Bitcoin 101 stands out like a blackeye.
The percentage of the hashrate controls the percentage of blocks won, which therefor controls the percentage blocks that the cartel can exclude non-cartel transactions.
While the percentage of total hashrate controls the percentage of blocks that said cartel can control, they can't control the others in any fashion. Control of blocks is not akin to control of transaction processing, nor is it akin to delaying of transaction processing. I can accept that, under some rather extreme conditions, such a cartel could force up the market rate for transaction fees, and perhaps backlog transactions with insufficient fees for a period of time if blocks are regularly full; however this is a far cry from the assumption that such a cartel can delay those transactions to any noticable degree. (It might be measureable, but not likely noticable to the average bicoin consumer/merchant) That all changes at the 50% mark, ut getting there is no small task. As I write this, the network Petaflops rate is roghly 1000 petaflops higher than when I mentioned it yesterday. It took three years to build the 33 petaflop supercomputer that holds the top spot worldwide.