Could also be useful if someone puts a typo in your email username when sending you an important email. You'll still get the email with a catch-all emails set up on your own domain. But you won't without this.
Even having a Gmail address doesn't make you immune from someone putting in the wrong address.
I made a throwaway/spam account with a silly name back in ~2007, and then in ~2015 someone established a fairly successful company with that name. I now regularly get job applications, tax documents, and employee timesheets to my email. They even signed up for the service that controls their website with my email.
I keep waiting for them to contact me about taking over the address, but as far as I can tell they don't even realize they don't control it.
