Prior to the P/F conversion the trend was to push Step 1 later in the curriculum, after the clerkship year. Like or not, since medical students are learning to become clinicians, there is logic to having the high-stakes national exam be a clinically-oriented one that occurs after third year.
To address to OP's question, high USMLE scores do not typically appear out of nothing. Medical students have years of data on exam performance before they take Step 2, and (big surprise) if you're a high scorer in the preclerkship years, and a high scorer on the shelf exams, and a high scorer on the multitude of commercial self-assessment exams, then you're going to do well on Step 2.
In fact, the students who end up being competitive for highly selective fields tend to declare themselves early on as being "total packages." The Step 2 score simply becomes a cap on 3 years of solid performance.
If the concern is that an otherwise mediocre student will have to wait until until late in the game to throw the Step 2 Hail Mary for ortho, then yes, that's going to be a problem. But not a new or surprising one.