You're thinking of the worst case. The reality is, in a large company, every promotion probably has 2+ people who have the skills and accomplishments. The determining factor ends up being if your boss likes you/wants to work more closely with you.
Yes, there are terrible managers and nepotism type environments, but on par most bosses wants to look good to higher ups which means promoting skills which helps the boss look good. Exactly what happened in your case.
> most bosses wants to look good to higher ups which means promoting skills which helps the boss look good.
…which is how you end up with stagnant cultures like Meta and Google, who just sit around and wait for their lunch to get ate by their competitors. If you instead reward delivering the goods in whatever context, you don’t run into these problems! The company should maximize for being a successful business, not stroking its managers egos.
Not just promotions, but jobs. After my second job, every job I've ever had I got because I knew someone who liked working with me and could vouch for my ability. I've never taken a coding test as part of a job interview. I did have to take one on the job once when a new manager came in. I left that job fairly soon after, as I found the whole process and attitude around it to be insulting.
Yes, there are terrible managers and nepotism type environments, but on par most bosses wants to look good to higher ups which means promoting skills which helps the boss look good. Exactly what happened in your case.