The relevance is that you said

> Nobody did use them though. They belong in an extension, it's the perfect use case. [...] every single unused line of code, let alone an entire feature, adds a maintenance, security, documentation and testing burden.

And the same holds true for Pocket.

It's not the same thing. At all.

Pocket is used by people and is a feature Mozilla want to prominently integrate with Firefox. This is due to the financial gains they directly get when someone signs up for Pocket premium.

It's not an unused, dusty feature that's adding a burden to the platform and is a net time + money sink. It's something that makes them money.

As I said, in the comment you just replied to, even if nobody did use pocket then this would be a burden they are willing to take. So, comparing RSS feeds to pocket on the fact that it can be implemented as an extension alone is a nonsensical point.

Pocket directly competes against the open web (in the form of RSS/Atom). If Mozilla was a values-based organisation they would be promoting the open web at least as much as they promote their own proprietary system.

If Mozilla offered a browser that people could pay for without having default settings to maximize revenue, the open web could be maintained.

The relevance is that at browser scale, it's the browser that drives adoption, not the other way around. Removing RSS support from the browser makes people use it less. Mozilla understands this, otherwise they wouldn't promote Pocket to browser core.