Let's imagine a scenario where you need to display some data from a remote service to the user. Instagram, for example. You want to grab the 6 most recent posts, pass them through some theming, then output them into a block.
I recently made the switch from Hostgator Shared hosting to a Linode instance, and WOW. It's amazing what you can do with a single (relatively small) box dedicated to serving up a single site.
If there's one thing I've learned about upgrading Drupal sites, it's that you're going to have to do the same 50 steps over and over and over again to fix things as they fail. It's awful, tedious work.