I cannot argue with that.
If I buy shares in XYZ Plc based on fundamentals at 550p without a stop and the shares oscillate between 570 -580p for a week or so, I will not be ecstatic but I will be mildly satisfied. I wake up one morning and find that the company has had a profit warning and the shares have dropped to 490p. Now I have a problem because I am nursing substantial losses and the company's situation has changed fundamentally (Profit warnings have a nasty habit of coming in pairs).
Quite frankly, I do not have a choice, I must cut the position and accept that I got it wrong unless it was an asset play.