Look, my view is this: it's not about maintaining N different interfaces.

Each news feed is totally personalized. This is done without having to worry about maintaining "N" feeds, it's built into the system, built into the approach.

Why is the design something that needs to be fragmented into buckets? This is a broader choice, accepting that all users need to be on some defined path.

You can measure and improve metrics without being concerned about the particular CSS file being delivered to each person.