Technology wise, sure. But I can imagine it could take a lot of effort to convert all refineries. And I think it’s much easier to crack heavier fractions than to combine lighter hydrocarbons to heavier?

If I understand correctly, we want more gasoline than the natural fraction in petroleum. So refineries "crack" longer molecules to create shorter ones, increasing the amount of gasoline.

I'm not sure if that's the gasoline subsidizing the heavier fractions. It might be the other way around. There would be more heavier fractions available if we didn't crack them, and therefore they'd be cheaper.

That still requires changes to the refineries, but even so, when the cracking is eventually turned off, the same mechanism remains.