> Socialists and communists are becoming more and more irrelevant in the modern era.

Leninists and their descendants might be; socialists aren't any more than capitalists are, as pretty much every advanced economy is some hybrid of the two. Because of the Cold War (by which point that was already largely true), it's become fashionable to call those mixed economies “capitalist”, that is not particularly accurate (though it comports well with Leninist propaganda.)