Anarchy is a crime

That which is not valid is a crime and in a liberal society if we are not doing a crime then we are doing something which is valid. If the state is valid then its opposite (anarchy) is not valid. And since to have a state would appear to be a natural function of the need to defend property from criminal individuals and gangs then the state can be valid.

If the state is valid then anything which opposes it and is in conflict with it (for no good reason) is invalid and criminal.

First-past-the-post is in conflict with the state because it is not fully democratic. Proportional representation (like direct democracy) is fully democratic which means that it is not acting in opposition to the state. Since fptp is in conflict with the valid state then it is criminal like all forms of anarchy are criminal.

Anarchy is criminal and first-past-the-post shares properties with anarchy because it is harmful to the state (which is valid).