These forms are indeed the "learned" ones, that derive from Ancient Greek. They have been solidified only in these cases at the doors. The reason we still use words like those with the Ancient Greek declination is a story that goes back in the 19th century, regarding the "Language Issue" in Greece. The answer to your question is yes and you could conclude to that.
But imagine that you are saying to your friends to pull the door. You wouldn't say "έλξατε" or "έλξτε", but you would say τραβήξτε ("τραβάω = pull" in Modern Greek). "Σέρνω" would be used only with the meaning of "drag", not "pull". And let's be honest, sometimes even Greeks might be confused with those. Not because of the morphology, but because of the change of the word.
More information about the Greek "Language Issue":
https://en.wikipedia.org/wiki/Greek_language_question
https://www.onassis.org/whats-on/milestones-history-language-issue-language-issue-our-language-problem
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Vasiliki Baskou, Instructor/Director, https://learn-greek-online.com.