How long has your career been? I’ve been doing software professionally for 20 years and the correlation I’ve seen is huge. Not necessarily inside a single company - but after awhile you get jobs from networking & people you worked with in the past. If none of your ex colleagues want to work with you again, it’ll become a lot harder for you to get hired & promoted.

15 years?

I've seen a strongly positive correlation over a 30+ year career.

It's not perfect, but it's far from zero in my experience.

When I see stuff like that I can't help but wonder if the people who are satisfied by it are the ones who fall upwards and of course say the system is working perfectly.

Maybe I fell upwards. Maybe I earned it. Doesn't matter for the following:

I'm now on the side of the table where I frequently make personnel decisions: hire, promote, offer a new role, offer a new assignment, merit adjustment, expand a successful team, disband or merge an unsuccessful team into another, transfer in, transfer out, put on a PIP, etc. Most of the good things on that list go to people who demonstrate ability and results, and rarely do those results come without effort. Most of the bad things on that list go to people who demonstrate an inability to deliver results, which is sometimes related to a lack of effort.