Past performance is no indication of future success. It doesn't matter what's been successful in the past, these things can change. Communism was considered more successful than capitalism for a large chunk of the 20th century (because it was), then that changed and so did the narrative.
None of this is settled, because it's a living system that changes over time. What may have been perfectly true in 1850 might not be remotely accurate in 2050.