Crude oil molecules are not polymers.
That is a different molecular structure than that found in naturally occuring crude oil.
But the subject is making long-chain hydrocarbons from methane, not making gasoline from asphalt. Where do you think the term "paraffin" comes from? The very high MW hydrocarbon fractions in crude oil resemble polymers quite closely.
"That is a different molecular structure than that found in naturally occurring crude oil."
I can guarantee you that the molecular structure of any saturated hydrocarbon is precisely the same as polyethylene. The only difference is chain length. And that holds true for both straight-chained and branched-chain hydrocarbons.