PCs are hackable by design. It's a perfectly mainstream thing to build your own PC from parts. Hacking toasters, on the other hand, is not mainstream. Best Buy sells toasters, but not parts for toasters.
I personally wouldnt draw the line between information appliances and computers at whether the manufacturer actively blocks you (as Apple and John Deere do), but rather at some combination of what the intended purpose is, and whether hacking and customization is considered mainstream or fringe.
Hacking toasters and dishwashers and microwaves and refrigerators is possible, but fringe. Hacking cars and houses is mainstream.
Is it? Most PC (or notebook) users buy whichever one is on sale at the store, or they use one provided by their company. This does not strike me as inherently different to how people buy toasters or dishwashers.
Of course, there does exist a niche of people who like building their own PCs, but this does not imply that this is the mainstream case.
"Unauthorized Bread" by Cory Doctorow
