the example is based on you having a page template in your theme that doesn’t display bbpress well, but works for other pages.
In that example you could use a different class for bbpress pages to get them to render how you would like. So you would have the if/else.
the article explains the other way, which is to rename a template to bbpress.php or forums.php, and then simply alter that for whatever bbpress display you want.
Finally if it’s only bbpress display that you want to alter, you can simply change the bbpress styles in your theme style folder.
Lots more in documentation, if you are trying to achieve something specific come back and detail it, and I’ll try and help