You're making my point for me.
Yes, if someone is deadset on buying a Series X, they're going to get one. Just like if someone was dead set on buying a PS3, they were going to get one, $600 be damned.
That doesn't mean that the millions of potential consumers that are on the fence or haven't decided on a console of choice won't be swayed by one console not being on store shelves while the other is sitting right in front of them at their local Target. That doesn't mean that the millions of potential consumers that are on the fence or haven't decided on a console of choice won't be swayed by one console being $60-$70 more than the other, bundled with a game they don't want.
Again, it's not an end-all-be-all factor, but it's unquestionably a factor. Take your blinders off and you'll see that.