I definitely agree that having "alone time" from your co-workers helps foster creativity because your mind wanders more when you're not engaged in a focused discussion.
It reminds me of how Archimedes discovered the principles of buoyancy and density in the bathtub.
37signals' approach to business is not at all paradoxical. It represents little more than tried and true business sense applied to the web. It's only that we've long been brain washed into thinking that the web is so different from other forms of enterprise that we've come to think that old style business models won't work there.
Work in a business you're passionate about, build something that you want and that people want, charge money for your products, keep your costs low, start simple, don't overwork yourself, etc. These bits of advice are nothing more than common sense in the brick and mortar mom and pop business world, yet somehow they sound like revolutionary, radical instructions when applied to the web.
It reminds me of how Archimedes discovered the principles of buoyancy and density in the bathtub.