I imagine a majority of Hexbear has never read Kapital in full, but they're still leftists. The point isn't that every leftist should tons of theory, but if you're in a position to actually make change (like Zohran) you should have read quite a bit of theory, so you can put that theory in action, or even maybe write that theory yourself (like Stalin, Mao, Lenin, etc.).

Think about the Vangaurd/Proletariat split. Some people understanding theory is important, so that theory can be applied and applied correctly, but the vast majority only need a simpler understanding so they can spend their time at the task at hand.

You don't need theory to become a leftist, but applying theory can make you a more effective leftist, and strengthen ideological cohesion.