Why do so many people here spend time picking stocks that are already a huge portion of the S&P?

I’m not somebody who believes in EMH and that it’s impossible to beat the market. But I do think you typically need a differentiated view (variant perception) and probably a mix of stocks that aren’t predominantly top 10 holdings in the index. It’s odd there is so little discussion here of small caps for a stock picking forum, IMO.

So many posts I see here are a mix of Tesla, Amazon and Google, or similar. Do people think holding these stocks in some magic additional percentage (in addition to the fact they are likely already holding these stocks via index funds) going to allow them to outperform for any meaningful period? Aren’t you just adding more risk and decreasing your Sortino ratio?

Advocates of this approach, what am I missing?