I'm pretty sure a good chunk of their topics are just personal neuroses and sexual impropriety
And we do have entire boards dedicated to sharing literature, though with NS history being a considerably narrower scope than the general history of "leftism", greater suppression of NS media etc. etc., it's not difficult to see why there would be, for one, a far greater breadth of material for the left to discuss (such a circumstance is also cause for more fractionalisation, general infighting and purity spiralling within leftist communities). With Zig Forums however, such debates of where to even align oneself are not commonplace, as the board is already a result of such consensus. We, shills, bots and botshills aside, already know where we should stand.
One could also look back at the histories and foundations of NS and communism themselves to observe where our culture may have developed. Germany, formed in the reaction to Bolshevik attempts at insurrection, had also promoted the freedom of arms and (like the Hellenic world) a cult of fitness, and sought to cement their national futures to the disdain of international finance and the collective physical, psychological and political force they can will to their demand - parallels that we also find ourselves on the 'underdog' end of today.
Meanwhile, China and the USSR constructed themselves on totalism and cult psychologies, the annihilation of culture (subversion language, history, national identity) and submission to dogma. The revolutions of Marx were sold on the idea of collapsing unnatural balances rather than balancing natural order, and the left remains consumed with this same baseless deconstructionism today. To rid the world of Germany and their Rothschild-extorting asses entirely, the Allies made temporary allegiances with China and Russia - allegiances that, after the main enemy was destroyed, were dropped like sacks of shit, and thus prevailed a decades-long campaign that we are still in the midst of, to discredit and degrade their influence entirely, culminating today in trade wars, sanctions, and accusations of political interference with the Democratic West™. So too, does Antifa currently enjoy the support of the aristocracy, being given largely free reign to carry out their violence by the mainstream press as long as We the Boogeymen are eventually stamped out.
Funnily, the left acknowledge that the dominating classes diverge from their ultimate idealist aims entirely, and yet, as evidenced by occasional forays into /leftypol/, still fail to make the logical leap to realising how the shackles they construct for us, and the endless regulation and clamping down of communication and widening barriers for 'hate' speech, will be used against them the moment it becomes more convenient. They don't feel the need to beat the system, because right now, they are the system. I have thankfully never attended American academia, but I sure would be curious to know the ways in which their ideas are fed to them as an ostensible solution to each of their insecurities: their broken homes and sexual inferiority, their bullying, their moral transgressions and even the religious impulses they deny the existence of. When all of these vacuums end up filled so adequately, it is clear to see why one might replace their prior worldview with that of the tribe, and given a (((convenient))) existential threat and enemy (us) to distinguish themselves from so starkly and so justify their own existence, direct an unrelenting amount of force, physical and otherwise, towards ending them.
There's another simple answer to the question though. There are those of us who learn from history, and strive to spend our lives to build and improve, and there are those that don't. They would rather sit around and circlejerk over something Popper might have said when he wasn't busy ripping the shit out of their outdated secular religion.