Nothing wrong with alternatives, but for that we need to let go of "let's make it just like the thing that also fails". We also need to acknowledge that socialism assumes that humans are fundamentally good, and that ignores that many are fundamentally not. We need to acknowledge that the core idea of socialism, the common good, is ill-defined. (Just like, while we're on AI, ideas of alignment on one value system suffer from that ill definition)
So, no, you don't get voted to hell for saying that the problem is capitalism. You do get downvoted for sloppy thinking if you simply propose "socialism will save us" because it's long established that in this form, the statement is not true.
Ultimately, the issue is that HN is not made for that discussion. You'd need nuanced political debate, and the internet does not seem conducive for that. That's the second reason for downvotes - HN is not interested in contentious political debate, for better or worse.
But no, it's not because we just all immediately think of the USSR/Maoist China.