Apple fans like to see apple UI guidelines followed on Apple devices, and Android fans like to see Android design guidelines followed on Android, but the normal non-technical users who don't really care expect facebook to work the same way on their android phone and their iPad and their work computer. People don't want to have to re-learn how to use the wal-mart app after their grandson convinces them to give up their old Galaxy S3 and buy the new iPhone. Expecting all apps to obey the platform guidelines is just as much hubris as ignoring the platform guidelines is.
it's unclear where 'at the cost of the user experience' comes in.
you say that good ui "doesn't get in the way", and later that platform windowing toolkits should be used to avoid distraction. this seems to suggest that platform toolkits are "good ui".
aside from branding, one driving force for cross-platform ui is that some don't agree with the premise of platform uis being "good ui".
> Think about it - how many people (as a percentage of users of an app) will use it on multiple platforms?
depending on the region, i'd wager a lot, actually.
> Hubris also comes into play. Obviously the UI models used in xxx platform are not perfect, but every app designer thinks "users will prefer this over xxxx's default, no question about it" (...)
do any compare various options and using their reason, experience and advice, and then conclude a particular choice is preferable because of it's properties and characteristics?
> (...) because they view their layout/navigation/ui/style to be the greatest thing since sliced bread and cannot fathom that users might actually prefer the device's native windowing/widget toolkits to their abomination.
how many people are we talking about?
truly it is terrible for the fascist designer to impose their design abomination upon the beleaguered users.
...but what about the liberated users no longer under the savage yoke of the gross and repellent 'native widget toolkit'?
More than once I have encountered product people looking at the app on iOS in one hand & Android in the other and explaining that they should be the same.
99.9% of the time, normal users don't do that. What they do is switching from one app of the OS they are using to yours.
Using the same idioms as other apps of the OS is more useful because this is what users will have been trained to use.
Facebook wants facebook to feel like facebook whether you're on an iPhone or an Android or your PC. Same with Chrome - it eschews native platform UI on all devices in favor of looking the same everywhere.
Good UI - by definition - doesn't get in your way. But "good UI" may not be "good marketing" or "good branding" and these companies are placing a premium on their brand at the cost of the user experience.
Good apps should _embrace_ rather than eschew the platforms they run on and their windowing toolkits so that their users can focus on the content rather than the presentation.
Think about it - how many people (as a percentage of users of an app) will use it on multiple platforms? (Windows and Mac or iPhone and Android?) How many people use facebook _both_ in the mobile browser _and_ via the app on the same device? (Especially given the obnoxious trend to block access to the website if a native app is available cough reddit cough pinterest cough messenger cough). Not many at all.
Hubris also comes into play. Obviously the UI models used in xxx platform are not perfect, but every app designer thinks "users will prefer this over xxxx's default, no question about it" because they view their layout/navigation/ui/style to be the greatest thing since sliced bread and cannot fathom that users might actually prefer the device's native windowing/widget toolkits to their abomination.