You're conflating "intellectuals" with "academic professors". Communism has been quite popular with college-bound academics for a long time, especially in professors in non-STEM fields, and especially in professors teaching undergrads. But the popularity wanes as people move away from college campuses and into other sectors.

In any other instance, if you described a certain adult as a person who, as they got older, continually hung out with 18-21 year olds, that fact would lend less credence to their viewpoints, not more.