TL;DR: Complex bans are bad and the OM leaders (TI, Sect, Drampa, etc.) are all hecka good at their job.Could you explain your reasoning for this
I want to first give SectoniaServant huge thanks for being of assistance in our decision.
If my answer needs more elaboration, I'm hoping he'll show up and fill any blanks. That said, I'll try to summarize some of the main points:
One of the big reasons for swapping from banning the moves to banning the Pokemon is that traditionally, when Smogon (and its councils) consider a problematic Pokemon, rather than just banning the move, the mon as a whole is evaluated. Dracovish is probably one of the most black-and-white examples of this. Without access to Rend, most people would agree Dracovish could probably have stayed in OU. The problem is that logically, you're creating a complex ban.
While the pedantry of course can vary, the general agreement is that a Complex Ban is a ban that has a conditional. Back in the day, Speed Boost Blaziken in OU was considered a problem, and for good reason. While there was some debate, the larger consensus was that if Blaziken didn't have Speed Boost, it could have stayed. The knee-jerk response is "okay well let's just say that X Pokemon is legal if it doesn't use Y ability". On paper, that seems fine. The problem is that a lot of Pokemon could change in tiering if they are given conditionals. If Zacian gets only, say, Work Up and Snore, it could probably be even PU. If we allow for bans with conditionals, we can definitely "add to the variety" of plenty of formats/tiers, but then every banlist becomes all but impossible to understand, especially to new players.
When we ban a Pokemon, the conversation doesn't need to have conditionals.
The second major thing is that Morytha and I don't really have much in terms of formal experience when it comes to being Leaders of a meta. I hope it goes without saying that in PS and Smogon, people don't achieve their positions on accident. When someone like SectoniaServant or Drampa's Grandpa comes to us saying "hey this isn't the way we do things", it's important to listen to them. That's not to say that there can't be a dialogue (and I'm sure they can vouch that I, personally at least, had plenty questions of my own), but it's extremely valuable to listen to our community leaders and do what we can to grow together, rather than try to "rock the boat", so to speak.
In terms of individual bans:
Melmetal is Ubers by default*. Generally, when we bring mons down, it's because their power level doesn't scale enough to match their previous friends. If we let Melmetal keep DIB, it is still really good. Now it also gains Multi-Attack, Milk Drink, Meteor Mash (which is boosted!) and a lot of other stuff. While our personal testing has shown that Melm could probably stay without DIB, for the sake of things that were explained above, that's just not in the cards. Maybe Melm could get tested to return in the future with DIB as the meta develops, but for the sake of stability, it stays locked up.
All jokes aside, we felt that Zygarde with Tarrows would have essentially been the same mess it was in OU, and it also stays locked up.
Electrify is the weirder one. If you're looking for a lengthier explanation, I'm happy to provide one, but we're essentially using a lot of the reasoning that was present in STAB for banning it. Pokemon like Manectric, Jolteon, etc. just create these really messy games and it puts an unneeded strain on teambuilding.
I hope that answered everyone's questions, and if you have any more, please feel free to ask!
* Edit: Melm is OU right now but it was Ubers when the decision was made. I didn't see that change. My bad! I think the overall point still stands