I don't think it is true.
When you first learn something about how to play, you can easily be thrown off by moves you haven't seen.
However, by the time you are a pro, by which I assume you mean someone is at least a master, you have seen thousands of possible opening moves. You won't be thrown off by a beginner's random moves.
I’ve heard people say that sometimes it’s harder to play against a beginner than a pro, and I’m curious about this. From my understanding, pros are predictable because they follow strategies and patterns, whereas beginners can be more unpredictable and erratic. Has anyone else experienced this? https://krogarfeedback.org