I've heard this argument before, and I just don't buy it. It's not a one player advantage, it's an advantage in every round. Go one step further and after team B takes their player at 30, you're right back to a one player advantage from the second round on. Not to mention that the odds of taking a hit increase substantially in that first half of the first round, so "just one player" (even if you believe that) is still HUGE.
But beyond that, the higher picks in each round have more value in trades, both to move around the draft and to acquire players. You can say it's not as big a deal as some people make it out to be, and I can't argue with that. Some people go overboard. But to say it's a myth that it's a noticeable disadvantage is simply not true.