Well using a replies templates as comments to blog posts is a feature for bbPress 2.7 I believe but if that feature is really key you should either  code it yourself or  look elsewhere cause waiting for 2.7 won’t be worth your time. The bbPress 2.7 release is at least one year away based on the current average development of bbPress.
From the other point of view, bbPress is the most easy to use forum software when it comes to making changes or altering the frontend layout when you have some WordPress experience.
I mean, I customizing the frontend of a ‘forum’ is what rocks my boat I never understand why people would use one of those most populair forum scripts out there and in the end have a forum that looks like a FORUM and completely different from the rest of the site layout. I always like it when everything, site, shop, forum and whatnot looks and feels the same as the general site.. I never create forums for mega large websites or sites that are driven by communities from the early days when you simply had to install a forum script to create a so called community. There are far better systems out there that just do that. Create communities and interaction with users – you don’t need a forum for that. Forums nowadays are generally for support only.
Your MacRumors example is a site that was created 300 years ago based on a forum system to interact with users. Now they are bloated have to hide mega lots of content to fit your mobile screen else the site would load 12min a page.
Myself I was making a bbPress forum today with a subject called ‘Apple support’. Just for fun not a real project. It’s just fun how easily you can alter bbPress templates and create something frontend that you didn’t know was a forum script.
This example is my Forums index page.
*still work in progress..
Replacing blog comments with topic replies is scheduled for 2.7, but you can also use the handy bbPress topics for posts plugin.
You can create custom roles with custom capabilities in bbPress.
There is an API or an example API in the Jetpack plugin.
There have been users trying to make apps with bbPress.
WordPress JSON Rest API bbPress and Android
Also know there has been work to introduce an API into WordPress.
And there already have been plugins in development for compatibility between the WP-REst API and bbPress like this one.
https://github.com/thenbrent/BB-API (Alpha version)
Any contributions for any work toward any type of bbPress Rest API are welcome and much appreciated.