It is too easy to come up with a lot of BS/inflated expenses to where profit is zero. In fact, everything you just listed (team salaries & expenses, advertising & marketing costs, and other business expenses) are exactly was is used to make sure profit is zero or less in Hollywood Accounting.
Given the shady crap that some of the big software companies pull with their own employees I can totally understand Apple wanting it out of the gross.
If you know what you are doing internet advertising is insanely cheap. Its formal name is Earned Media and is considered the holy grail in advertising because it is effectively free (compared to Owned and Paid Media).
LOL. Tell me you don't do any internet advertising without telling me you don't do any internet advertising.
Once again, you're treading into areas that you know very little about except for some articles you've read. You're not actually in the trenches running a game company, or clearly ANY company that relies on Digital Marketing.
Internet advertising is NOT cheap. Costs have skyrocketed in the last few years and competition has grown 100-Fold. Just for mobile apps it costs about $2-$4+ for ONE INSTALL of an iOS game (free games, not paid) from a US user (one of the best markets) and that often won't be profitable.
This "Earned Media" PR stuff or from organic marketing (that yields much) is very RARE. Everyone and their brother is hoping to get a bunch of free publicity and traffic for their game. Again, it's not that easy or everyone would be doing it. Therefore, PAID advertising (FB Ads, Google Ads) or sponsorships (such as with YouTube channels or Twitch broadcasters) are the only feasible option and it's far from cheap.
Facebook has over 10,000,000+ active paid advertisers on their platform that account for 98% of their billions in revenue. As someone that has spent a small fortune on FB Ads over a few years, I can tell you it's far from cheap. Yet it's the number one resource for advertising ANYTHING being sold online, including Apps or other software.
As for the Gross vs. Profit and the commission, I'm not saying it should be based on profit in a pure sense where companies would have to self-report their accounting etc. as that would be a nightmare. But the 'fair' amount of what % the commission should be based on should be with what estimated profit margins for developers are, not gross revenues. That's why the 30% is incredibly high and it could account for over 50% of Net (and does) for many developers. That's reason in and of itself why the commission should be lower, something more like 12-15% max. Taking 50%+ of someone's Net is a JOKE.
And dude... stop playing the "whataboutism" game in regards to Apple's 30% and what others are charging in an attempt to defend Apple. Apple established that monopolistic high price on their App Store that they fully controlled and others (Google, etc.) followed with the same 30% because Apple established they could get away with it. Nintendo wasn't running a comparable digital marketplace like the App Store or Google Play Store or how Steam works in the present day.
Just because a bunch of huge companies, that in many ways don't directly compete with each other, start charging 30%, doesn't make it right nor fair to developers. Especially when developers can't provide their players with alternative payment methods.
Apple and Steam may both charge 30% but they aren't really competing against each other. They have near monopolies on their marketplaces. Apple for iOS titles and Steam for PC titles. Epic investing $500M+ and still not making a major dent in Steam's business (yet) is the first company that has come along and tried to challenge Steam.
So some sort of price/commission comparison between actual direct competitors like McDonald's, Burger King, Wendy's, etc. is far different from companies like Apple, Microsoft (Xbox, not necessarily PC), Sony (PS), Google, and Steam that have grown so big they now have protected monopolies over their own marketplaces. A developer can't go and sell his iOS game on another marketplace, because there isn't one that works with an iPhone. Same with the Xbox or Playstation. There are some other marketplaces for PC games, but Steam has such a lock on the market and so many millions of users that use Steam to manage the games they own and play (and friend connections, etc.) that it's extremely hard to sell a PC game outside of Steam and have much success.