You can tell people who criticize the "radical left neo-marxists" know very little, seeing as they seem to think leftists can agree on anything, ever, at all.
Conversation
Radical right wingers: "Okay, we hate all these people. Let's exclude them from society. Deal."
Radical left wingers: "Yo, I really don't respect your reading choices. Let's spend the next hour dissecting your political positions and excommunicate you if we disagree at all."
Replying to
It really isn't hard to understand why there is a fascist-nationalist upsurge even though those ideologies are pretty meh.
There is no compelling alternative that doesn't immediately fracture into 5 different splinter factions of niche interests or intractably specific idealism.