I think firstly is the FOSS obsession and backdoor paranoia from evangelists, and secondly and the more practical one is that the proprietary IBM BIOS is full of bugs and anti-consumer blacklists and whitelists designed to limit repairability and upgradeability, which stil boggle my mind on how those laptops got such a good image on that front.
I mean, maybe paranoia is the wrong word.. it's not something that I'm personally worried about, but stuff like that has actually happened.