High rates only used to be a thing because the content you're playing through was aimed around low rate - so on a x99 exp high rate you'd basically smash through all the dungeons in an hour (pretty much ignoring half of the game) and be level cap to enjoy end game content. This worked when the original files were first leaked as no one knew how to make anything other than the basic layout of dungeons and mob.
On private servers however, people specifically build a high rate - so you still go through all the content at worth while pace, collecting items etc, then eventually you'll hit the end game content. This is in fact just a low rate server with a few zeros added on to everything.
Your eyes are deceiving you. Its like exchanging your British pounds for Vietnamese dong and suddenly thinking you've become a millionaire.