I think the main question is if mobile web applications will be able to match native on both quality and performance.
Facebook attempted this and failed badly, but that doesn't mean it can't happen or that native will always have an edge. If native does continue to have an edge though then I think web has an uphill battle.
In many ways it still is - it requires too many permissions and the list is growing. Recently they're asking for access to my SMS messages and in Android 4.3 I had a bug with my Nexus 4 in regards to location services as the Wifi-network provider was draining my battery and so I had to disable it, so Facebook's app was still requiring it, activating the GPS on each opening of the app and there was no way to turn that off, unless I turned the GPS off globally. Granted this is also a failure of Android's permissions system, but ...
The mobile web interface was and is still there. It doesn't matter if the mobile platform is new or old, it doesn't matter if Facebook's app was developed (and approved) for that platform, the web interface is there and it works, the only requirement being for the user to have a decent JS-enabled browser.
People view Facebook's investment in their mobile web interface as a failure. I view it as competitive advantage.
The iOS app is an example of how much better a native app can be from the web app - and the new paper app even more so.
I remember the android one being terrible when I had android phones a couple years ago - but I thought that was because it was basically a wrapper around a web app.
What if history repeats itself? What if iOS will in the end fail in the marketplace, reducing its share to a single digit? What if Apple continues against all odds to develop and support it, like it did with the Mac OS? What if you'll still use it?
Wouldn't you be happy then that there's a web interface available?
And from a developer's perspective - you could say that you want to target iOS users first. That may work out well for you. However, for example, I never, ever tried Instagram because when Instagram was all the rage, it wasn't available for the platform(s) that I'm using. And later the momentum for me was gone. That's a lost opportunity.
In the end, it may work out well for the developer - however, considering that iOS's marketshare is minuscule compared to the people that have access to web browsers, I personally don't see how you can build the next Google or Twitter or Facebook by not targeting the web first.
For another example of companies that failed to do this - WhatsApp Messenger will probably die or get acquired, because Facebook is eating its launch, as Facebook works everywhere and when I send a message to my wife, she either reads it on her phone, or in the browser tab that she keeps open when on her laptop. FB's messaging works on my iPad too, whereas WhatsApp doesn't because WhatsApp is identifying users by their phone number.
I suppose mine was more targeting the difference between mobile native applications and mobile web wrappers.
Facebook's web interface for 'real' computers is great and companies that don't have one would probably benefit from one for the reasons you mentioned.
On the mobile side though I still think native applications are worth the investment and that'll be hard to change unless the web apps can actually offer similar design and performance.
I'd love to be wrong though.
Now consider what it would take to build the next Final Cut Pro. You could try to do it as a web app, and you might even get some casual users who don't need much capabilities. But you are not going to displace existing professional tools on any platform.
Being available everywhere just means you're not better anywhere. Java apps discovered this last decade.
Huh? My perception of the Facebook iOS (iPad) app is that it is badly, badly broken.
It opens links within the app and there is no way to override this behavior.
This means I can't browse Facebook-sourced sites alongside everything else I'm browsing or bookmark those sites in Pinboard. I can't even copy & paste the URL from the Facebook app into mobile Safari.
I uninstalled the Facebook app within minutes of downloading it. The web interface just works better.
Gmail - email client
Mog - Music player
Google Voice / MightyText - Messaging
TweetDeck - Twitter client
Confluence - Team wiki
Trello - Organizational tool
Toggl - Time tracking
Bitbucket/Github (I suppose you could debate that these are just websites)
Google Drive - Document editing and storage
Would these run better as native apps? Probably, if you're just talking about raw performance. However, I frequently jump between OSX, Windows, and Linux machines. When I open Chrome on any of these devices I can pick up right where I left off. Could I say the same with a native app? Probably not. For me, the performance of the web version of these apps is good enough, so cross platform compatibility becomes more important than raw power. That's what I meant when I said it depends on your definition of inferior.
I don't think mobile hardware or mobile browsers are quite there yet. But I don't see any reason why they won't eventually get to a point where they're "good enough" for people like myself, at which point other factors beyond raw performance will become more important.
Though I guess I usually have my laptop with me anyway.
[1] http://facebook.github.io/react/
It's also been a couple years. Mobile processor perf is better and JS engines are faster.