Can WP/BP deal with large community sites?

Sigh! I'm researching a site I want to build which will be a community website like a dating site but not a dating site. It will need all the stuff a dating site needs though. I have been looking into hosting and software and my hosting is sorted. I can upgrade with someone like Hostgator and then when the time arrises, move to a dedicated server. Anyway I've just discovered that a large community website needs a solid (whatever that means) programming platform to handle all the files etc. For example I think Perez Hilton has his site on WP and I know he gets millions of hits per day. But now I know that a blogging framework doesnt need such a strong platform cos its just posts etc and not much data stored. Im determined to get this right and want to get off on the right foot. I think Id like to start with WP/BP, appropriate themes and membership software and then if its successful, get someone to build it from scratch with the programming I will need (whatever that means - I dont really get it). So - does anyone know of any WP/BP high traffic COMMUNITY sites that are up and running? Many thanks.