Can't be sectarian if everyone's being mocked equally
It's also not saying that those groups are bad, just that they need to focus less on idealism and theory. Something we all basically agree on now. Can't have a workers party without organized workers.
Another thing that's massively changed over the past 100 years is that worker orgs are not reliant on petty bourgeois/bourgeois "intellectual" class traitors anymore. The working classes of all countries now have natural intellectuals coming from their ranks thanks to literacy, education, and access to information that was once impossible for people who had to spend all day working.
You don't need people who only read about working class experience leading thought for working class organization, you have plenty of well educated and informed people who actually are working class.