I still agree with your last paragraph. In gaming as in professional life, a T-shaped skillset is really useful. Having broad knowledge and experience, even if it's mostly shallow, is incredibly useful.
Yeah, I could certainly see that but I disagree with your assessment that it is just pandering or self-soothing.
Seeking out any external information in your off-time / outside from that activity gives you the edge against people who just show up and only engage and think about the activity while doing it.
If you are watching basketball play-by-plays or even better, recordings of your own games (read: consuming transformative versions of games just outside your skill vs passively consuming a professional game) outside of basketball practice, there is a good chance you will pick up or develop ideas of how to apply that to your own game.
Yes, passively watching someone play WoW has a low chance of making a world-first raider but watching a world-first raider do raiding with the intention of picking new ideas up will expose you to ideas and methods you won't otherwise be exposed to through normal gameplay.
By listening to other engineers speak, you are being exposed to problems and solutions you would have had to encounter and solve yourself (or possibly never have so you will never cross pollinate ideas)
See there's the mentality I'm calling self soothing. Your mental model of what makes someone excel seems to build off of what you like to do. One thing is to pursue extra information, another is to believe the sole way to excel is by doing the things you do.
People actively looking at top 10% players can have more game knowledge and build efficiency than people who just grind bigger numbers.
Being an "effective" software engineer also depends on your definition of effective. Mark Zuckerberg was clearly an effective software engineer, but was he in the top 5% of engineers?
People judging their abilities by adjacent (and loosely correlated) metrics is a road to unhappiness.
"When a measure becomes a target, it ceases to become a good measure"
And he is „only” in like 99,9th percentile in time trials, not even competing in top tournaments.
The concentration of knowledge that was available in a (successful player's) stream was far more useful than what I could gain from personal experience playing alone.
Sounds like pandering to the audience. Performing better then 90% of people makes you a top 10% player.
Self soothing about how what you like to do in your spare time makes you better then others is not making you any favors.
It doesn't matter how much effort you put into being effective. In fact I'd say living and breathing software engineering will make you a less effective software engineer than someone who also understands management, psychology, economics, etc.