100% this.I find whiteboarding to be the actual scourge, as it involves unrealistic pressure in an unrealistic scenario. It reminds me of tests that inadvertently just test whether people are good test-takers versus assessing their command of the actual subject matter.
I believe hiring devs who are also good at whiteboarding have a bias--even blindspot--where candidate whiteboarding is concerned. They oddly believe it to be a prerequisite for a job that infrequently or never requires it.
As such, they may miss out on good devs who simply thrive in an environment more akin to reality.
In the case you describe, you've already done the more "valuable" dev work of thoughtful analysis/design, and you are merely presenting that work.
That's far different from being forced to devise that design at the whiteboard, singlehandedly, with onlookers.
That's not to say that devs don't hash out designs collaboratively via whiteboard (yet a different application). That certainly happens and is useful. But, you're likely to find that--even in those situations--team members have considered the problem offline prior to the collaboration.