[…] I have personally never been injured or visibly endangered by working on any kind of computer system, much less a consumer notebook computer. I have also never heard of anybody else being injured by working on one.
They do have a point here though; everyone's seen those laptop batteries on fire. That shouldn't stop someone who knows what he's doing from being able to fix things, but having some incompetent "I'm going to save a couple of bucks and do it myself" DIY:er muck about is probably going to lead to disaster sooner or later.
P.S. As a specific example, combine this with the original all-in-one-box Macs' shitty power supplies (and co-located video tuning controls, now that I think of it), and you had a not too uncommon reason for people to go poking around the CRT.