You could ask the same question for virtually ANY accelerator program out there. And at the end of the day the answer is, "it depends."
Every founder and every company is different. If you are a first time founder and your network is limited then these programs open a network you could never penetrate on your own.
For seasoned founders these programs help to connect you with resources as if you had additional team members meaning (if you took advantage of it in the right way) you could easily scale your business quickly.
If you are a founder who is sensitive to your early valuation then an accelerator may not make sense.
Every founder needs to sit down and collect as much input as they can to make the most informative decision to help grow their business.