OTOH, my laptop has more in common with a VAX running Unix than it has with a Commodore PET. Or a LINC.
This was my thought upon reading the "Big computers and little computers are completely different beasts" quote, and it's also something I've been thinking about lately. Personal computers definitely represented a distinct development track from the multi-user/multitasking industrial/academic computing systems of the time. However, as PCs became more capable and merged key innovations from the higher-end computing branch (e.g. virtual memory, protected execution environments, and the operating systems that can leverage such features), we seem to have arrived at the same point -- a phone in my pocket that's more like a VAX 11/750 available in 1981 than an IBM PC from the same year. The "microcomputer" development track that included the Commodore PET and 8086-based PC systems was greatly useful for jumpstarting the PC industry, but was ultimately set aside.
So maybe it's not so much that small computers are completely different beasts than large computers, as their initial development required a unique approach to fit the constraints of that particular era.
As someone who has personally installed UNIX on a VAX 11/750, I do appreciate the attention to human factors that the microcomputer era has contributed to computing. :)
Their evolution is pretty cool. And their software is very alien to people who grew up on personal computers.