Kind of ignores the fact that socialism did take root, like Eugene Debs running for president, but it was violently uprooted and the ground was torched and salted and a massive state apparatus was developed to make sure it could never be entertained again.
Someone running for President multiple times and never clearing either a single electoral vote or more than 6% of the popular vote is certainly evidence of their personal determination, but hardly evidence of them representating a philosophy that had taken root.
If Eugene Debs running for president proves that socialism did take root, how do the later runs of Norman Thomas not argue against the torching & salting?