Because 92% of Democrats want communism.
Communism, in any of its guises, is a command-and-control form of government, and as such, is antithetical to the founding principles of the United States of America.
Once the agreement is made by the voters to put one of these command-and-control operatives into office, usually by making long promises that cannot possibly be kept, the machinery that tends to protect incumbents kicks in, by distributing perks to the voters of the districts, and also by various forms of fraud at the ballot box. When the number of these command-and-control operatives reaches a critical mass (usually about 10-20% of the entire legislature), they can effectively block any actions to stifle further encroachments of government upon freedom. It is not necessary to gain a majority to effectively rule the nation as a whole, it is only necessary to crush all criticism before it rises to the level of general discontent.
This requires collusion on many levels in the society, which in and of itself is not criminal activity. But criminal activity may be engaged in, through the pursuit of this collusion, through both suppression, and the dissemination of disinformation to the public at large.