what's so crazy about it? Bookies like Pinnacle or Betfair aren't accessible from many/most countries anymore, so an agent gives you the possibility to still do so. That's imo the main reason for most people to use them. And it's a very valid one.
If you're happy with what else you have access to, sure, no need to use an agent.
If you're happy with what else you have access to, sure, no need to use an agent.