That's a pretty standard opinion on this topic. I don't really think it's noteworthy.
The punching up vs punching down thing has become a bit of a platitude though. What people generally mean by it is comedy that does not target ethnicity, gender, sexuality, or disability and does target wealth, power, sometimes whiteness, and ignorance from privilege.
That's pretty clear cut and sounds like a great guidebook to what should and shouldn't be made the butt of jokes, but in practice nothing actually adheres to it completely and where the line is exactly is pretty poorly defined - and that's just the way it's going to be, because comedy isn't just about whether a joke is 'fair' or not, it has to also actually be funny, and sometimes the funniest thing lies in territory that is right on the line and you are not sure what side it falls on and that is part of what makes it funny. There doesn't always have to be an element of transgression in comedy but that's how the concept of comic relief works - where there is tension, a joke is made. The joke itself doesn't have to be completely fair, in fact in that situation, if it was then no tension would really be released because it doesn't target those areas.
Hope that makes some kind of sense, it's a pretty slippery topic.
Also, punching up and punching down is really about power, rather than the various categories I mentioned before. It is where there is a perceived power imbalance in society that the seat of the power is identified as a worthy target for derision. However, even the big proponents of punching up vs punching down will use stupid people and strange people who don't fall neatly into this power imbalance as the butt of jokes. Somebody has to be the fool, or else what are we laughing at. Since white men are put at the top of the power imbalance, they are by far the ones most often made the fool, because it's generally accepted they can take the hit. You can verify this by looking at where the worst, most hackeneyed comedy happens - tv commercials.
So comedians who want to try and throw new light on things will understand that playing it 100% safe and making the white men the target of every joke is basically on the level of a tv commercial and might try to find different fools in their jokes.
I think everything has to be taken case by case as to whether it goes too far, or starts to target vulnerable people in society in a mean-spirited way. The punching up vs punching down thing is fine as a starting point but like I said, it's become a platitude and I don't think it's a good thing for comedy to just take it as set in stone. You've got to fuck around with it and find those tension points. The laughter in those areas comes from the tension itself, and might even help relieve it for the people who are laughing.
