It's not reductive - it's literally what they did. Some weapons are given out early and/or made accessible to everyone early on. Those are going to get more use than weapons that are harder to get, regardless of their utility. I can't recall if it was once or a few times, but on the update I'm thinking of, Bungie *only* used usage and popularity to justify nerfing weapons. Specially, my favorite and most used PvE weapons.
I agree with what you said in general, and as a process it makes sense. But it's not always what Bungie did, especially in the back half of Destiny 1's run when they got really aggressive about whacking down popular PvP guns.
Obviously personal preference, but I hated using MIDA in PvE without high impact rounds. The stagger ability is critical to how I use it, chaining headshots together as enemies stagger. It felt like a pea shooter that made us move a bit faster once the high impact rounds were gone. Of course, this happened concurrently with updates that
gutted snipers, which at that point were the only secondary weapon I still enjoyed using (after shotguns were rolled back to a state worse than the shipping game). So there was a cumulative effect of hitting my favorite primary and the entire class of secondary weapons that I used. (Weapons I used in part due to abandoning ones due to how severely they were nerfed.)
I should note again that I'm almost entirely a PvE player. I didn't play Crucible until many months after Destiny shipped. (True story, my first PvP game was with a couple of Bungie folks. They didn't believe me that I'd never played it until achievements started popping. :lol) I
still haven't played Crucible in Destiny 2. I respect that balance is much more fragile in PvP than PvE. My overarching request is that they balance them separately, or offer mode specific perks. For instance, in the case of the MIDA, "fires high impact rounds when fighting non-guardian combatants".
My great fear is Destiny 2 goes down the same path Destiny 1 did, where the content got better and better, and the PvE sandbox worse and worse, because of PvP balancing. I'm already upset that the entire loadout system for Destiny 2 was overhauled with PvP in mind (there are so many weapons stuffed into the Power slot that I don't ever touch 90% of them). That's what I'm on this particular high horse for.