Well we all assume the fund manager is not James Cordier or Bill Hwang. And they would have the stops there by default.
Stop losses are not a panacea from preventing or limiting risk. All you guarantee is that you're out of a position, but you still have uncertainty around what your total pnl will be on the trade. Most pro's use risk management techniques such as managing portfolio covariance and betas to factors in order to hedge downside exposure. Others use drawdown techniques to mimic convexity (like an option payout).
Because of the way a stop loss order works. It submits a market order after a price at been touched. So instead of you thinking you will get out on a 2% drop, you end up with a much larger loss.
But the trade is still over. I agree you don't know where your exit order will be filled and gaps can cause bigger losses than you planned. It happens but not that often. Having a method of getting out of your losing trades is still the best risk control I have found.
I don't. I'm not trading odd lots using charts either. Most professionals will set "soft exits" where a position will be reduced/exited regardless of thesis, but that trade will typically be done through a different order type than a simple stop loss.
Risk management needs to be consistent. If it can break (overnight gap, random volatility) then you can't rely on it. It may protect you for smaller moves, but will have significant tail risk events. I'm not saying not to use a stop loss, especially if you're trading 10-50k at a time, but there are lots of other strategies to improve risk that you may not be aware of.
Traders (most or otherwise) do what they do and neither you, me or anyone else knows with any certainty what most do. Meanwhile saying a P&L is unknown with a closed trade is just ignorant. BTW ever heard of a thing called limit order?