In a lot of organizations, software development is secondary, so the machine you get is going to come out of some system that does a mediocre job of procuring machines for salespeople and secretaries. If you're lucky you get a new mediocre machine, if you're not you get a hand-me-down laptop from a salesperson who couldn't sell.

It doesn't make any sense, but 70% or so of people who hire developers don't seem to look at this rationally. On the other hand, they usually don't provide you good specs either.