I have a theory called trotksyist survivor theory. Basically nations with strong histories of McCarthyism have Marxist-Leninists purged, persecuted and killed, since they are usually more active in grassroot movements and actual agitation and organisation. Trotskyists meanwhile where less threatening and confined to intellectual circles, hence survived without much persecution. I came to this conclusion after reading about Communism in my home country, Pakistan, and realised many other countries also fit this pattern, like USA and Indonesia.
From Reddit.