There was never a real division between them. Islamic Socialism has always been supported by Nazis and Communists alike.
Classically these entities are eventually defeated or frittered away through intrigue and conspiracy within the ranks of the army.
In more modern times the permanent bureaucracy tends to be the agency of destruction ~ we saw that in the disintegration of the East Bloc, and then the Soviet Union.
China is following a similar path but they have a far longer history of accommodating TOTALITARIANISM than does the West. That's why we still have the top strong man, his council, their army ~ but we also have a nearly independent financial, industrial and consumer products sector.
China for all its current prosperity is still just 15 minutes away from utter disaster ~ virtually 100% of the industrial sector workers have part time jobs! There's still no reliable large scale oil source to keep it going. More than half the people continue to live in traditional Chinese villages surrounded by pigs, ducks, rice paddies, lots of dirt and poop in jars and piles.
The Chinese are well prepared to continue living in near subhuman conditions ~ and that acts as an incredible drag on the existing order all the way to the top.
As a lesson Sun Yat Sen undertook 50 different 'rebellions' or full scale local wars before he could overthrow the totally discredited and despised Manchu regime!
BTW, that wasn't all the rebellions ~ other guys were holding rebellions as well as his movement ~ with fully equipped armies wandering about, etc. When the regime collapsed there was a degree of warlordism as the Chinese pulled the of government back on THEIR TRACK ~ Sun was the President of what seemed to be utter chaos for a good long while.
Still between Sun and today China went through numerous upheavals and is probably better off today than it has been for several thousand years. They are still loath to give up TOTALITARIAN methods.
Noteworthy in all this they've identified islam as a competitor and are exterminating it ~ while appearing to cave on the spread of Christianity.
So, about the leftwingtards in the West ~ their attraction to islam is simple. It's another TOTALITARIAN philosophy that has a track record of some degree of success. At the same time most of its adherents live in utter poverty surrounded by jars and piles of poop, with chickens and cattle wandering about, and what seems to be a plentitude of feuds and murder. The Leftwingtards probably imagine they can improve on this ~ (Bwahahahahaha)