Normal non-corporate cross platform should be WebApps, that is even worse than Multiplatform Frameworks like Xamarin or QT. Normally, the only way to make an application feel and behave native is use their own native API and language (Objective-C or Swift for macOS/iOS, Java for Android and, well C# for Windows UWP).
Said that, general App quality is not the same in iOS than in Android, not because developer competence, but for the platforms. Think in iOS as a High Tech Car, Android as a dirty truck and Windows Phone... Well, thing Windows Phone as a dead skull...
Paying 600$/year is not a big issue for a company, but for a standalone developer could be his yearly app income. More if he need to pay 600 for iOS, 600 for Android and about 3000 for each desktop. Sometimes app income is not so much, and risk so many amount before know if you are going to get at least those money back in sales, for a home-brew developer, is a no-scenario.
Problem with Dropbox, as I understand the platform, is it is not a "drive" but a cloud. You must download from cloud each time you need a file, and iCloud, now with iOS 10 and 11, is a drive that replicates into the cloud. And consider pay 120$/year for 2 TB instead of 1TB Dropbox... I paid Dropbox but as I started abandoning Windows platform except for work, I prefer to pay for iCloud. Currently for 200 MB but will pay for 2 TB when needed.
Te blog post I refer before was a rationale about the current problem with Store application model, that tend to kill developers in flavor of the users. It is not a complain about subscriptions, of course, but companies must understand that people cannot support pay 500$ in monthly fees for subscriptions to Evernote, Dropbox, iCloud, Ulysses, Day One, Microsoft Office, etc... (BTW, I use Day One, but as I'm old user, I have enough with the current free account).
PS: Oh, man, you have me make go back to Marvin!
