The largest stomping boots belonged to people like Stalin and Mao, who were far from conservative and ostensibly for equity. History tells us who's interests they cared for.
Many people with power will attempt to retain and increase their power by exploiting others, regardless of their political ideology or the social system they're part of - it's human nature. Their corruptive success may be mitigated by suitable social organization, but my contention is that social Marxism will actually increase their success.
A primary goal of conservatives is preserving what works, at the expense of attempting alternatives. I'm not broadly conservative, but on this issue I think it's worth preserving the values that allowed the West to prosper. Judeo-Christian values like virtue and work ethic. Enlightenment values like individualism, free speech and personal property. Modern values like mass education in science and reason.
Postmodernism deconstucts and equalizes everything. It has no respect for what works in the real world or how difficult it is to evolve relatively stable and fair societies.
If you think the corruption in our current system makes it untenable, how do you propose stopping corruption from once again infesting a Marxist replacement? Would it not be better to patch what we already have?