A “graduated” project might find it easier to get adoption, contributors, as the guarantees (stability, integrity, security, governance) are some of the criterion that org use while deciding on tooling.

It’s basically saying: If you were shying away from using Istio in production, we graduated, take a look now?

The graduation criteria I care about is "Have completed an independent and third party security audit". Lots of software in the cloud native world puts security in the back seat sadly!

It's a statement that it's not some personal project and it is backed more or less consistently by a bunch of people.

Funding can be attained more readily if you have a project that reaches any of these stages.