Yes the "there were always 2 parties" is the illusion I spoke of.
In a FPTP system if the underlying real support for parties is red: 40% blue: 39% lib: 21% then the vote will come out as something like red 51%, blue 49%. However in the next election if the real preference shifts than the vote will immediately and drastically change as well to reflect the new party.
In other words, while the votes themselves will give the illusion of a two party system by converting true support to a 2-party vote outcome not reflecting true support. The real underlying support will not reflect a 2-party system and there will be **no** preference for the same 2 parties to win from one election to the next.
We see this with the historic changes in parties, in every election where a new third party becomes dominate within a single election a previously near 50% party shoots completely down to less than 2% and the third party immediately shoots up to near 50%. In other words the numbers move rapidly and shifts in primary parties easily change.
So again this doesnt reflect a 2-party system, just an illusion that reinforces the myth and thus is self fullfilling.