Knowing your customer lets you take shortcuts. For example, if you have a monorepo, you can do a code search to find all usages of a function and fix them, instead of going through a formal deprecation process.

There is a tension here between efficiency and privacy. Inside a corporation with an "open" culture, you can be a lot more transparent and efficient since you don't have the same privacy issues.

Open source projects can sometimes do similar things, for example with the Linux policy of having device drivers in-tree.