Counter-study to your counterpoint (better than sharing random anecdotes): https://www.sciencedirect.com/science/article/abs/pii/S03044...

From the abstract: Findings show that early career artists have the least social capital, established artists have the most, and late career artists begin to lose social capital unless they actively maintain it.

What about the corollary logical leap that is social capital is a measure or predictor of success at the workplace.

I think burden of proof is on you to demonstrate that social capital is not needed for success at workplace.