I don't care if they dip into other classes. What another class adds can't be used to show wizard superiority. Either the WIZARD is superior, or it's not and needs help from other classes. Needing help =/= superior.
What
would show Wizard Superiority in your book? Your point is moot if in your eyes nothing will ever show Wizard superiority, regardless of what it is, which seems to be your stance. So let's not have shifting goalposts or impossible standards, what is it that specifically would need to be shown, in order for you to say that Wizards
are superior? Genuinely, it's ok if the answer is "for me, nothing would cut it", but then just saying, you don't need to constantly insist that something "doesn't show it", since for you that would always be true.
Not everyone plays at a table which disallows long rests until the DM decides the players get to take advantage of the benefits provided. By RAW, those can be triggered by the players without DM permission. You've already indicated that if folks Don't run 6-8 encounters between long rests, the casters Will be imbalanced, and it's their fault that such would be the case. But at high levels, you literally can't prevent them from taking a long rest whenever they want other than via DM fiat, houserules, or endless world-ending clocks always forcing immediate actions. Not all tables are comfortable with any of those, and I don't think it's fair to then indicate the unbalances arising as a result of just following RAW for long rests is all their fault.
Stealth advantage to be unseen, sure. Not to be silent. Invisibility would provide no advantage against being heard.
The rogue would at least be quiet.
Right up until he gets eaten by something that can see invisibility, has ears and can hear the unstealthy clod, has blindsight/blindsense or a sense of smell. Which means lots of things.
You refer to a Wizard as an "unstealthy clod" in a system where literally all classes have the same access to the same skills, and say that if they Do go invisible, then they'll still get eaten by just about anything under the sun, because being invisible doesn't help. So how then would a ranger, druid, monk, or anyone else fare? Or even just a Rogue which didn't use expertise on Stealth, since they're potentially identically skilled, and
don't have invisibility to help? It's a weird look to argue that invisibility literally does nothing to make you harder to detect, just saying.