Well, stock pickers work for companies so I'm not sure how to deal with that distinction. I think it's logical, though that the best stock pickers will work for investment companies whose track records are public. So, with that I think there are three different ways to approach the question:
1) If someone does know how to pick the superior investment advisors, they aren't telling. Here is a pretty good video on the subject: Dr. Kenneth French on picking a manager:
https://famafrench.dimensional.com/videos/identifying-superior-managers.aspx
2) Coming from human psychology, if someone did have the skills to be a consistent winner, why would they be selling their talent to retail investors or even to an investment company for a relative pittance? IOW, if they exist we won't have access to them anyway.
3) Fifty years of research all points to the fact that the best model of the market is randomness with a slight upward bias. If the market is indeed random, then all investment results come from luck, including streaks of wins once in a while. IOW, while the existence of streaks sometime somewhere is predictable, winners can only be identified in the rear view mirror.