I don't like spending this much time arguing against campism but they just keep talking at me.
No, the essence of the term is "bad leftist" - it has outgrown its historical context.
The majority of discussions about "tankies" are about leftists that refuse to vote in an approved manner: anarchists are "tankies" according to social democrats, social democrats are "tankies" according to liberals, etc etc. You use it to mean "leftist that supports Marxist-Leninism" but that just isn't how its used by the majority of people. For the majority it's just a snarl word.