I agree with what many have said. I don't have the betas, I don't even have iOS 12. I'm on iOS 9, but, contrary to what Apple does with many settings (it moves them around, ALL the time, for no apparent reason other than to just... change), this is a regression.
Why couldn't they keep the tab? This makes no sense, at all. It seems it's another of Apple's "change for the sake of change".
Obviously, the intent is to promote the Arcade gaming thing, given the fact that Apple removed the Update tab in favor of Arcade. Since that won't be full-blown until iOS 13 is released and developers start releasing the Arcade games, it seems a bit pointless now. However, whether or not you agree with how Apple is doing this, it's NOT pointless, and not a "change for the sake of change" - there is a method to their madness ... Apple always has a motive... and like many here, I may not agree with this move, but then, I don't have the time, the funding or all the necessary skills to create my own phone operating system, so I choose to use Apple's. Even with these warts.