[bratbag]

Because feature flags often intersect with segmentation and AB testing.

So it's not just a byte in memory, but often also correlating the status of said byte with a users identity and then tracking and summarising user behaviour based on that relationship.

It's become fairly standardised and requires engineer time to setup and maintain the services behind all that, so it's valid to go third party for less than the cost of said engineer time, if all you want is standard.

Edit:it's also hard to always predict when a standard flags going to become part of a test, so just integrating for every flag and making that a standard process for your teams becomes the simplest approach.