Reinforcing my statement that 700 bst Zama was dropped down from Ubers to “balance” a collection of broken OU mons. Rather than just cleaning out the trash and letting the hundreds of lower tiered mons shine, Zama is one more added threat in OU that really has no business existing here. But if it keeps Kingcheap and Ogerbusted at bay, it is good for the tier!
I find it a fallacious argument to appeal to the idea that "hundreds of lower tiered mons" would manage to shine in OU (hyperbolic or not) to advocate for Zamazenta's ban whilst arguing the latter as OP for checking several high tier Pokemon in the tier. Even if the Pokemon many are arguing to be unhealthy like Sneasler, Gholdengo, Iron Valiant, Manaphy, Ogerpon-W, Kingambit, were removed from the tier, a large majority of the remaining Pokemon are min-maxed to shit (with or without Tera) and don't give a lot of breathing room for Pokemon without either equally optimized stat spreads or a lot of useful role compression (see Tusk putting Treads out of any OU job despite the latter's arguably better typing for a Spinner role). More to the point, nothing was stopping those lower tier mons from being experimented with beyond people simply not wanting to try them in the Meta, whether they wouldn't work or they simply didn't catch anyone's eye.
Hell, if you're going to cite a 700 BST mon being dropped to "balance" broken OU mons, I can point to actual precedent of Kyurem-B, which spent 3 Generation viable but not dominating OU because it had multiple kit pieces that sandbagged its other useful traits into OU-reasnoable viability likes its movepool, mediocre typing, and awkward speed tier. BST means literally nothing as a citation, which I'm sure you're aware of, but it's the only point you managed to cite in two posts about the mon compared to
yNot Mence whom you were following up on at least noting several constrictions they feel on teambuilding that Zamazenta causes them, whether that is unhealthy or a hurdle for how they play in particular. If anything Zamazenta's high BST is the thing holding its less-than-optimized kit together (and the form we kept is 660 BST Hero, the 700 BST Crowned form went for a myriad of other reasons alongside those stats).
More to the point, the tier's not obligated to allow any specific Pokemon to thrive. Zamazenta was dropped into the tier and then not deemed worthy of a re-ban because it wasn't found to be egregious in the tier it was in. If it's pushed for a ban then that needs to be proven in the Metagame where that advocation is being made, not the currently-hypothetical Meta where several things it checks have been banned. Why do any of the unspecified lower tier Pokemon who haven't demonstrated a known niche have more right to viability than Zamazenta, who has not demonstrated a net "Negative over Positive" effect on the game and has, if anything, demonstrated a useful place in team building?
Many people already agree that Kingambit and to a lesser extent Ogerpon-W should be evaluated and possibly banned, so I don't get what this implied ignorance/conspiracy is about Zamazenta being unbalanced but keeping them in check to make it and them "better" for the tier.
Kyurem Black was banned as soon as it's flaws (sans ice typing) were solved: lack of reliable ice stab off of its physical attack. It also got DDance which certainly helped. The issue with Zamazenta is that it's both offensively threatening and a defensive pillar while still being really fucking fast, often times at once. Notably, Kyurem White has never been allowed in OU because it's always had STAB moves for its higher attacking stat, so I don't really think the Kyurem Black analogy really works.
The analogy is ultimately referring to Kyurem-Black before those moves were added to its kit, which lasted for 3 Generations. KyuB's eventual ban doesn't really disprove the argument: that the BST alone doesn't define the Pokemon as banworthy and its kit needs to be evaluated Holistically, rather than pointing just to a number. KyuB became banworthy because the additional moves coupled with its other traits became a Sum that was too strong for OU, but obviously we have a number of Dragon Dance users with High BST and good STAB options that are not remotely problematic in that gen or this one, as it included other factors like higher bulk to offset its defensive typing and a useful ability in Teravolt, for some examples.