I imagine that most Superinvestors don't want to hold BRK as it leads to questions from investors about why they should be invested.

A lot of money managers don't want to hold Berkshire for their clients because, once the client is convinced that it's an excellent choice for a big core long term position, they ask...why can't I just do that myself? Why pay you? I have had a client say exactly this to me. Conversely, if the client isn't convinced it's a good pick, they will not want the manager to pick it for that reason. So, whether the client likes Berkshire as a pick or not, the manager won't be admired for holding much of it.

After all, money managers aren't in the business of managing money. They are in the business of collecting fees in return for managing money.

Fisherman to tackle salesman: Do these really fancy expensive lures work any better for catching fish?
Salesman: I don't sell lures to the fish.

Jim