Marxists who aren't concerned with orthodoxy generally self-identify as "Socialists" rather than Marxists, even -- perhaps especially, given the degree to which Marxism as a label has become associated with Leninism and its descendants -- their approach to socialism generally follows Marx as opposed to other socialist thinkers.

There are also Utopian Socialism, so socialists in general is a larger group than Scientific Socialists.

But more seriously, I think you're conflating revisionism and orthodoxy; just because Marxism is changed over time doesn't mean that it accepts all changes.

(And by Marxism, I mean Marxism, Marxism-Leninism, and M-L-M. There are a few smaller tendencies as well within all these broader traditions.)

To be clear, when I said that Marxists who aren't especially concerned with orthodoxy tend to identify as "Socialists", I did not mean the very different claim that persons who identify as "Socialists" tend to be Marxists who aren't concerned with orthodoxy.

Yes, socialism includes a lot more than Marxism (and did before Marxism even existed.)

And, no, I'm not conflating revisionism with orthodoxy. My experience has been that people who generally adhere to Marx's views but are not concerned with a narrow orthodoxy of a specific approach tend not to identify as "Marxists", and those that identify as "Marxists" tend to be very keen on the orthodoxy of a very specific interpretation or evolution of Marxism (predominantly, an orthodoxy oriented around Leninism or Maoism as the One True Marxism, though sometimes not.)

True, my top comment certainly conflated them - it was a throwaway but a rather lazy one, plus I have a rather jaundiced view of Marxists, critical theorists, and similar groups.

And libertarians seem very concerned with adhering to the letter of a 226-year-old piece of paper. Being concerned with orthodoxy isn't just a Marxist thing.