I agree with you, but I will add one thing - separation is a multi-faceted concept. Gaining separation through route running is the primary concept that most of us think of, but the ability to position your body and win contested catches is, at least in my opinion, also separation. It's just not what most of us think of. Certainly, though, the attribute of creating separation through speed and running routes with strong breaks and effective fakes takes precedence over fighting of body positioning Still, whether it's route running and athleticism or body positioning, either of which results in a throw where the QB can place it only where the WR can snag it has value, particularly when we are talking about where on the field the ball is thrown. Dante Pettis in between the 20s might have more value than Courtland Sutton on the sideline and redzone throws. But in the red zone and 3rd and mid-long, Courtland Sutton might have the advantage. It's all about scheme and the QBs strengths (not to mention, of course, the WRs strengths).
When I look for a receiver, I'm looking at both (and this goes back to the analytics and where it has some merit, but not the entire merit), but I have to assume the QB can make the desired throw - not the collegiate QB, but in the NFL. Receiver 1 might create separation for YAC and gain a first down over the middle of the field, but Receiver 2 could run a deeper route and win up high or over the sidelines. Put those two things together and you have a means to achieve the goal for that play. Of course, we all know football isn't an equation and any number of things can go wrong, the QB doesn't set right, pressure comes up the middle or outside, the player in coverage is holding the receiver and doesn't get called, or he makes a spectacular play. None of these things compute mathematically, and that's precisely because football can't be reduced to equations except maybe probability. Naturally, you have coaches and scouts who develop their preferences based on what they see and take in the analytics and athletic measurements as a confirming measure of what you see on tape. They may lean towards the tape or the analytics a little heavier than the other, but to disregard one in favor of the other is folly, and that's what I think the guys on the podcast got wrong.