proxies like customer/revenue growth, complaints/satisfaction and such works imho.

Missing part of discussion is “what for?”.

To make personnel decisions who to fire or give bonuses it doesn’t work. Just as lines of code don’t. If any of those indicators is lacking you have to dig deeper.

What lazy managers want is a single number they don’t have to dig into to make decisions. Lines of code, story points, bug counts.

To plan work for next sprint having last 6 months of stats gives quite good idea what can be achieved. But story points or stats are not useful for telling if specific features will be developed in specific timeframe.

How can you assign revenue growth to a particular feature?

Even if the customer tells you they bought your product because you added widget x you can't really be sure.

So much of this stuff is emotional rather than rational.