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Yeah, I agree that size is a definite factor for a AAA game. I don't think I have ever seen a game that I would personally define as AAA that came from a developer with less than 100 devs, at least not in the last 7 or 8 years (Skyrim's dev team was under 100 devs but that was in development from 2008-2011, Bethesda increased to about 140 core devs for Fallout 4 plus an additional 50~ devs at support studios, and now Starfield's team is over 250 core devs just at Bethesda Game Studios itself). For instance Ninja Theory called the first Hellblade AAA, but it wasn't really, they made it with just 20 devs and it was only 6 or 7 hours long as a result, there is a reason it released for $29.99 instead of the typical AAA and large scale AA price of $59.99 at that time. They seem to be going properly AAA with Hellblade 2, with both a longer dev cycle and rumors they have 100+ devs on Hellblade 2 now.
In fact I'd say budget is less of a hard rule than team size is. While some AAA's these days have budgets in excess of $100m, we have seen recent AAA games with smaller budgets, sometimes much smaller than $100m. While it has been 8 years now, Witcher 3's budget was $81m at the time which is $93m with inflation and that was a 150+ hour RPG in a 100+ square mile open world, I'm sure there were smaller AAA games this past gen with lower budgets than that. It was reported that Resident Evil 2 Remake's budget was under $100m back in 2019. Ubisoft reportedly made the first Watch Dogs for $68m and the first The Division for $50m. And then there was Control, definitely AAA in graphics quality, length (30ish hours of content), and dev team size, yet Remedy themselves reported a budget of just 30m Euros or $35m USD for it.
