hi5 (RIP) was originally a dating site and Pivoted to a Social Network.
Most profiles fake? I can say for sure that's not true. I maintained Postgres/Memcache/Graph DBs and the write load was real.
That said hi5 did engage in address book scraping and other dark patterns that you'd rather not see these days.
Fun fact: hi5 had a featured photos/profiles section based on popularity. Folks that ended up there deleted their account by 5x or more due to the unwanted attention their 'popular' photos garnered....