i agree with you on the fact that a person who has no idea how to do it should stay at least 5 feet away while its being done or use compressed air (which due to its dryness also causes static electricity, in fact all friction, regardless of the elements used, does according to physics, the amount is just different)
actually anyone who has no idea what they are doing should stay at least 5 feet away from an open computer case
BUT using right materials (low powered vacuum cleaner, plastic vacuum cleaner tip and a non synthetic SOFT brush that has all metal either isolated or has no metal at all) and right techniques (prevent fans from moving to not create charge with their coils, keep the vac cleaner tip at least an inch away at all times and brush the dust into it) you minimize, if not eliminate the risk of frying your pc