Sounds like a conspiracy theory unless you can prove any of the transactions did not have a legitimate purpose (or completely lacked miners' fees). It makes far more sense to me to align incentives in the system such that so-called "spam attacks" are costly and ineffective, and thus irrelevant. Simply examine graphs of Bitcoin's transaction growth over it's ~8 year history. It was always bound to run into the 1 MB limit eventually, whether such "spam attacks" actually exist or not.