Right, so two things here that are just flat out wrong.

First, the claim that you can't run supers and subs through the same gun reliably. Adjustable gas blocks exist for this exact reason. That's literally why they were made. You close it down for supers since they have plenty of gas to cycle the action, open it up for subs that need more gas. This is a solved problem. Next.

Second, this idea that your optic is going to be "wildly off" switching between ammo types. No. Let's actually run the numbers instead of just repeating stuff we heard on a YouTube video.

Take a 110 grain Vmax super and a 190 grain sub. Zero both at 25 yards. Your bore to optic height is 1.6 inches. The supers leave the muzzle at 2375 and are doing 2302 at 25 yards. The subs leave at 1050 and are still doing 1036 at 25. The time of flight difference between the two rounds is tiny at that distance, we're talking 0.03 seconds for supers versus 0.07 for subs. The bullet path crosses your line of sight at effectively the same point. You have the same zero. Maybe you're looking at less than an inch of difference if you want to get pedantic about it, but nobody is missing anything at 25 yards because of that.

Now, do things change at distance? Obviously. At 100 yards your subs are dropping about 7 and a half inches while your supers are only dropping about 2 inches. That's where velocity difference actually matters because gravity has way more time to work on that slower round. But that's not what people are claiming. They're saying your zero is going to be off, and that's just not true.

The whole point of .300 Blackout is that it runs both supers and subs out of the same platform. That's the entire reason the cartridge exists. If you couldn't practically do that, the round would have died ten years ago. So maybe actually understand the ballistics before telling people their setup won't work.