Thanks for sharing these thoughts! I see your point generally.

If we didn't do this we would have nobody to celebrate, since almost everyone is found to be fundamentally erroneous given enough time.

I think you interpreted my point in a different way than I meant. There is a distinction between holding some erroneous assumptions and logics than being significantly wrong. It also matters what is the reason for praising a historical figure. As I wrote, some people, despite proven wrong or inaccurate later may have contributed to development of ideas. Contributions also differ in their directness and magnitude. Marx was not a pioneer. Critical attitude towards him would even suggest that he or his followers even mislead economics and social theory, and continue doing so even after 150 years. For these reasons people should be careful when they celebrate Marx. For me and many others it seems very unclear what they are eventually celebrating.