But where did they say they only used each device for 1.5 years? That seemed like your assumption based on the quoted dozen laptops across twenty years; I certainly have a number of devices concurrently, with the oldest now being 14 years (still working though only on a power supply as the battery is badly degraded). That said I also strongly prefer a replaceable drive, but more because I don't want to buy the capacity at today's price that I'll only truly need in a few years time, if ever.