This is a beautiful quote because it is an example of one industry's bad behavior leading to another industry's bad behavior, upon which the first industry then users the second's similarity to justify themselves. Cars only started doing this because phones made it normal. It's wrong in both cases.
It's similar to when Apple defended it's 30% store cut by claiming it's an "industry standard"... specifically, an industry standard that Apple established.
A sibling comment notes that Steam charged 30% at the time (though some had better deals) but it's worth noting that Steam was not an open platform that anyone could publish on. Much like for consoles, to put a game on Steam you had to have a preexisting relationship with Valve, or try to develop one with no certainty of success. This was also considered a very generous cut because getting on Steam was almost a guarantee of financial success.
No, it wasn't. I'm not going to dig up links, but one could pop a web site storefront and Fastspring for payment processing (as one example of a company I used) for less than 10% (Fastspring would take something like 6-7%, IIRC). Discovery has always sucked on Apple's store, so no value-add there. In fact, I'd argue that the only value-add one gets out of Apple's store is access to their closed garden.
And "50-90%"? Is that in reference to putting software in physical boxes and on CompUSA shelves? Because no mobile publisher charged 90% before Apple's store came along.
For the Apple case: access to the walled garden is the majority of the benefit. But still, setting up payments, customer service, chargebacks, fees, etc., is nice to have taken care of. 30% nice? Who knows. But more than just the raw payment processor overhead, surely.
AFAIK physical boxes are way above 50%.
But there's 2 reasons the comparisons aren't valid:
1) The revolution Apple brought to mobile phones was making them personal computers. So the relevant comparison really should be with personal computers and I doubt any of them had stores that took as much of a cut.
2) More relevant, the vast majority of such app stores which charged 40-50% were optional marketplaces. A customer didn't need to go through them to install an app on their phone (I believe Palm was like this. I'm pretty sure the likes of WinMo allowed many different ways to install apps). So if a marketplace was charging 40-70% it was entirely for the fact that they were bringing a customer to you. If you were able to acquire a customer by yourself, you didn't need to pay anyone any cut.
The big problem with Apple's 30% cut has always been that they charge you that amount just for having a user, even if you did all the work to get that user to use and pay for your app. Outside of the maybe 3% credit card fees, Apple provides 0 value.
One may argue (as many Apple folks do) that they charge for the frameworks, etc., but that argument is absolutely backwards. Apple creates the frameworks and APIs because they need the apps, not because the apps need them. If Apple was to get rid of its 3rd party APIs and frameworks, so there were no 3rd party apps, it's not the app developers who would suffer because all those users would migrate to Android. It's the iDevices and Apple that would basically disappear.
In fact, App developers would be thrilled because now they only need to support 1 Operating system.
If this is a personal computer, solely because it runs a browser, then the goalposts have shifted dramatically.
Most of the limitations you mention like compiling are completely arbitrary and added by Apple. The devices are powerful enough and it's easy enough to do everything on a $300 Android phone.