It matters because he specifically mentions that the team "didn't want to have to make a business justification everytime someone wanted to fork a repository".

Yes, but that doesn't imply they're justifying a financial cost. It could be that they need to justify creating a new repo and figuring out how/where to host it.

They wouldn't have to, if they were on Github's maxed-out plan already. There is no higher tier. They're already paying the most. (hypothetically)

The maxed out organizational plan ($200/mo) is still only 125 private repositories.

GitHub is just not financially feasible for small organizations with many small, private repos. For small teams like mine (3 + an occasional contractor) that have close to 200 repositories of closed-source code, $200/mo is laughable, particularly when we can host all of that on BitBucket for free because we never go above 5 users.