I think it depends on what is meant by 'everything'. Some functionality goes together very well. Some might not. Certainly from a social media point of view, the ability to do a twitter-like post, a full post, a photo post, a video post, a fitness post, etc. from one app seems reasonable. I don't need or really want 12 apps to post to hive. That's like carrying around 12 slightly different hammers. On the other hand, I don't think it necessarily makes sense to integrate various block chain games into one app. 

As far as the financial aspect, the web based interfaces have always had that integrated (at least from a user perspective). It's just a matter of how well.

Mobile apps are horrible for how stupidly they are focused. Every restaurant and retailer has their own app and for the most part it's the same as a web interface anyway. 

I guess what I'm saying is that there is a balance. Integration is good where it makes sense. That doesn't mean it is good for everything.

Yes. And keeping the example on the software field, it is very convenient to be able to easily install thousands of softwares from the software depositories on the various Linux distributions. And you can customize the entire Linux distribution to your liking. You can even build it (the entire Linux distribution) from scratch. Like filling a big drawer with your most used, favorite tools.