Two countries with similar population, ample space and natural resources, won their independence from the imperialists around the same time, started out at around the same level of poverty and underdevelopment (China was actually slightly poorer and even less developed), yet the socialist one in the long run performed noticeably better. Now visiting the two countries the difference is night and day, you don't need GDP graphs to see it.
Not that GDP is a perfect measure of progress for a society... in fact it leaves out a lot and it can be inflated artificially by financialization and rent-seeking in neoliberal systems (not the case in China).
What you don't see in this is the incredible development that took place in China pre-1980s starting in the 1950s in ways that was not reflected in GDP but laid the groundwork for the future economic rise: education and literacy rates, industrialization, infrastructure, housing, food security, etc. This is why socialism will win. It is the only viable model for the global majority to escape their colonial imposed underdevelopment.
Would be interesting to filter out the U.S. (and maybe other imperial powers) from the "world" line.
Indeed. It would also be interesting to filter China out from the world line because China's rise in itself is a big contributor to the world's average.