it has been done in the past with Camomons (although it was a different case, less inherently stupid move but much more distributed) (Siamato threatened me to not use that example because it's different...
Always easy to threaten smaller than yourself hehe
Since you have chosen to tread this slippery slope by using this comparison, I must clarify a few points that are important to take into account before possibly coming to the
nuclear (given the current policy) conclusion that a move should be banned.
Distribution
From a tiering policy point of view, a move can be seen as the issue from the time too many mons end up being banned
due to this move. By this I mean the move is a common factor mostly inseparable from the broken character of these mons: it's one of the reason if not the reason making these mons broken.
The threshold at which we consider the move to be the issue is often not something fixed and depends on some other parameters (2 being the minimum).
Calm Mind, in SS Camomons's case, was a move with a wide distribution. It was not hard to find about 10 users entering the unhealthy/broken territory due or partially due to Calm Mind (now imagine if, in addition, those 10 users have several viable typings...).
On the other hand, Belly Drum in SV AAA is a move that is currently abused by 2 mons: Hariyama and Chesnaught (although this last is more hypothetical at this time). I'm not considering Belly Drum as a critical point in Iron Hands's ban (Sword Dance is more than enough to make it still broken in the current metagame to me).
Impact on the metagame
Any tiering action should always look at the state of the current metagame. It's a way to decide what's a "confort ban" or a "necessary ban" for instance. Confort bans often get rid of something fishy and uncompetitive but whose impact on the metagame is somehow small due to this element not really wrapping the metagame around it. Necessary ban, on the contrary, get rid of an element centralizing and really impactful on the metagame.
Calm Mind users completely wrapped the old SS Camomons metagame around them. It was about how to counter opposing Calm Mind users and abuse yours well. Calm Mind users were a strong limitation to diversity due to their centralizing aspect. Moreover, having followed the way of banning mons didn't really solve the issue and even created other ones. If I will not come back on the matter here, the ban of CM in SS Camomons falls in the "necessary ban" category.
In SV AAA, Belly Drum is used mostly by 1-2 mons that are overall quite mid due to their inconsistency. They don't wrap the metagame around themselves but constitute an unhealthy presence due to their ability to somehow autowin if you didn't take them into account in the builder; something that is restrictive considering they are mid. Getting rid of either Belly Drum or those 2 is then mostly a "confort ban". It will not drastically affect the state of the metagame but will be still an improvement by removing a MU fish and uncompetitive element. Ban Electrify last generation was a confort ban too for instance.
Collateral damages, win/lose ratio
Let's say the point from which the discussion between continuing banning mons and banning the move has been reached. How do we choose what's the best option? It's about collateral damages and win/lose ratio.
If you banned some mons that didn't have a huge impact on the metagame and still have to ban some of the same ilk, probably you have to continue banning mons. That's especially the case if banning the move creates collateral damages by affecting the movepool of some other mons.
Now if you had to ban some really impacful mon and still have to ban one, maybe you better look at the move. Simply because the value of the move for the metagame could be lower than the value of these mons, even without the move.
Latias, Latios, Reuniclus and Slowking-Galar were all important mons in SS Camomons due to their positive aspects as defensive or utility options. It was also the case of Necrozma and Clefable ending up to be on the radar as well due to Calm Mind sets being dumb. Chosing to ban Calm Mind allowed to keep those great mons in SS Camomons and it was for the best (even though collateral damages were also quite large).
About SV AAA now, banning Hariyama and even Chesnaught will not be really impacful for the metagame considering those mons don't have any healthy aspect (especially Hariyama). The same applies to Belly Drum however. Other Belly Drum users are almost completely unviable and then losing the move will not change their viability. Nevertheless, banning Belly Drum could open the way to a return of Unburden that can be seen as positive for the diversity.
I'm not giving a conclusion if either Belly Drum should or shoudn't be banned from SV AAA. The purpose of this post was just to give the important points to take into account when it comes from opening the Pandora box and talking about banning a move. If banning a move shouldn't be forbidden from a tiering policy point of view (and is not in fact), it's essential to understand why we try to avoid them and that a solid justification must be brought to make it.
I certainly don't want people to make the shortcut of "Camomons banned a move last gen so why couldn't we do the same here?" without understanding how different these 2 situations are. The comparison with Electrify last gen is probably the best one if any.
I didn't mention Triage but it's also impossible to decorrelate it from those Belly Drum mons being unhealthy. The tiering policy in AAA allowing to ban abilities by concept, I think that's also on the table. However banning Triage will probably create more collateral damages than another option and why it should be avoided to me.
Thanks for reading as always (even though most of you didn't read ik)!
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