There are tons of similarities between tankieism and neoliberalism. Many tankies on Reddit go to S4P to argue in FAVOR of free trade, and I've seen someone on SLS say big business is better than small business. Tankies and neoliberals are also more likely to oppose free speech and call the white working class an unjust "labor aristocracy." In general I think tankies have lost touch with the emphasis on the "little guy" that, in contrast, allows the Dirtbag Left to expand its appeal beyond college campuses and other "wacko," culturally charged left-wing milieus. You can imagine a churchgoing father of two from Peoria listening to Chapo Trap House and voting Bernie in a way you can't imagine him donning a Che Guevara T-shirt and screeching about "social imperialism." I think a return to humility on the Left, a rediscovery of the spirit of FDR, WJ Bryan and Eugene V. Debs, and an abandonment of the '60s counterculture will be both advantageous and vital to any resurgence of the Left precipitated by the Bernie movement.

Edit: I don't know much about UK politics but to the extent I know anything just by general impression this is probably what makes the difference in popularity of Bernie and Jeremy. From a cultural standpoint, Bernie is from the populist left and Corbyn is from the socialist left if that makes any sense. Melenchon seemed like he was in between, making a solid effort to appeal beyond the cultural left but still possessing the "Trotskyist in college" schtick.