Well.... euuhh... why not? I know you can also use Wordpress (WP) for this and add/ intergrate bbPress in it, but why make it hard for yourself? For some it's very hard to get WP and bbPress work together and if you get it working it still has flaws (like registrating). Also, all the plugins (and future widgets) that work with bbPress will work with bbPortal.
Though bbPortal hasn't got all the cool stuff from WP, you CAN blog with it and it only requiers a simpel bbPress install.