Brent has a good post about Mail clients and OS X, which you should read. When I was in Seattle last week, Gus and I discussed email clients with him over beers. We also tried to talk him out of actually developing a mail client. Don't get me wrong, I'm sure Brent could do a fantastic job - I just think it's a terrible market. Thankfully, Brent knows this.

In his post, he said one thing that strikes me as particularly insightful:

"The thing is, there is little economic incentive to create an email app when one comes free with the system and that free one is good. For most people it s easily good enough, if not great...But if there is little incentive for other folks to create an email client, that means that the needs of keyboard adepts will go wanting, since Apple (rightly) concentrates on other things."

This echoes the first two laws of Rogue Amoeba, Don't compete with free and Don't compete with Apple.

We established these rules after working on a string of MP3 players for much too long after iTunes came out. Really, we never had a chance, and neither did anyone else.

Since its rather meek 1.0 release back in January of 2001, iTunes has turned into a juggernaut. To beat it you'd either need to replicate all of its functionality and then add more features, or go the other way and create a very simple player. That first option just isn't tenable. You'll never have your own music and movie store and you'll spend all your time playing catch-up on support for the latest iPod. And AirPort Express. Oh, and Apple TV. But, uh, good luck to you Songbird.

That leaves the "beautiful simplicity" route, and while there's something of a user base there, there's no market. You might argue that simplicity sells; the iPod, which lacks plenty of the features found tacked on to other players, such as FM radios, wireless communication, and more, not only sells, it dominates. But the iPod doesn't sell based on austerity or simplicity of design, it sells based on simplicity of use. You just can't sell simplicity when it really means "a lack of desired features". A free competitor to iTunes could quickly gain users, as there's almost no barrier to switching between audio players. But when there's no money to be made, there's no market.

Safari, on the other hand, really hasn't slowed browser development. There are a wide variety of browsers on OS X - Camino is widely used and Firefox is also popular. Omniweb and Opera are still kicking, and there are even new browsers, like Shiira and Flock. One key difference here is the use of open source (shared) code, which makes development easier. More important to note is that the paid browser market, which never had much of a footing, does seem to be pretty well dead.

So, web browsing, music playback, and email, three of the most important and widely used operations on a current computer. Apple offers built-in solutions for all of these tasks. To be sure, quality solutions need to be available right out of the box, or the Mac would appear incomplete. By providing these solutions, however, Apple has made it impossible to sell software in these markets, and in some cases slowed innovation. This isn't just Apple either, as Microsoft offers the same free functionality in Windows, via Internet Explorer, Windows Media Player, and Windows Mail.

Put simply, the OS is taking over. Third-party (or paid first-party) software used to be a requirement to get your computer to do much of anything, and the OS was little more than a GUI on top of a file system. The balance has been inexorably shifting, however, and now tasks that were once the realm of third-party software are considered basic features. By including these features as part of the OS, mainstream computing advances, and that's a very good thing. However, putting more in the box also causes third-party development to be, well, boxed out. That's certain to leave out more than a few users like Brent, who desire more niche solutions.