Yes, and it's not a sound argument, IMO.

"Grasping concepts" is not the only learning goal in schools or universities. Many classes - including within STEM programmes - want to teach students about writing, argumentation, researching, critical analysis, dealing with feedback, etc.

Oral exams can be more stressful, depending on the student. They also don't check for the student's writing or researching ability. They can be gamed with rhetorical skills. Grading of oral exams tends to be more opaque. And so on.

Then there's the issues I explained above, where you don't want to inadvertently reward cheating. Even if you don't care about the cheaters, you should try your best to detect and reward real effort. Otherwise, it'd be stupid not to cheat and use the class for free credits, at which point, from an educational POV, it's a useless class.

So, all in all, there are still very good reasons for doing take-home written responses and essays, and good reasons for wanting to detect cheating or plagiarism.