Never underestimate the fanaticism of an Apple (NASDAQ:AAPL) fan. I've known it for ages, but my inbox wasn't forgiving last week when I wrote about the impact that Amazon.com's (NASDAQ:AMZN) entry into the MP3 music downloading market would have on Apple.

"Apple really doesn't care who is selling the music," one reader wrote to tell me. "They are selling the thing that plays it."

"Let's review the score line when Amazon has sold three billion songs, shall we," wrote another.

I was iAmbushed. I survived to tell the tale, though.

The name game
A few readers had a little fun with the "Amazon 2, Apple 0" headline that I chose for the story. One rewrote it as "Apple 5, Music Labels 0" while another offered up "Apple 1, Fool 0."

If I can offer a quick refresher, last week's headline is a nod to the "Amazon 1, Apple 0" article that I wrote a month ago, when NBC migrated its shows from Apple iTunes to Amazon Unbox. I went with these headlines because Amazon has now taken two shots at Apple's iTunes business over the past few weeks.

This doesn't mean that Apple itself is a zero. Heck, short of the flawed Apple TV, Steve Jobs is as close as you get to King Midas these days.

I mean, is there anyone who doesn't admire Jobs these days? Last month's TechCrunch40 conference had a keynote trio of Yahoo! (NASDAQ:YHOO) co-founder David Filo, YouTube co-founder and now Google (NASDAQ:GOOG) rock star Chad Hurley, and serial Web entrepreneur Marc Andreessen. They were asked whom they admired the most outside of their own companies. All three picked Jobs.

Think about that. Three industry legends who achieved success by going against the herd mentality actually caved in and surrendered the same answer.

So who am I -- little ol' me -- to take swings at Apple? It's not easy, especially since I've been bullish on Apple dating back seven years, when it wasn't cool to show Apple some love.

If the screen cracks, you must subtract
I keep thinking of my 13-year-old son. He's the kind of Kool-Aid sipper that Apple covets. All he wants for Christmas is an iPhone and a Macbook. He's not likely to get either, but the fascination stems from his iPod addiction.

Here's the problem, though. Those iPods? They're as collapsible as this season's New York Mets. My son takes pretty good care of his things, yet he's on his third iPod. It's not a generational thing. The screens on his first two iPods broke. The first was his fault. The second accidental smash came at the hands of his cousin, where it somehow managed to crack even with a protective cover. The thought of those big iPod Touch and iPhone screens sends cracked shivers down my spine.

His upgrade decision each time was pretty simple: another iPod. He's reasonably sharp when it comes to money, but his iTunes music and video collection warrants going with a pricier Apple digital media player than a cheaper rival to simplify the transition.

Things will change once free-flowing MP3s dominate the market. Amazon, Wal-Mart (NYSE:WMT), and even Apple are starting to sell them. Even if one argues that Jobs has always been a vocal supporter of downloads free of DRM (digital rights management) shackles, it's a platform that levels the playing field.

Sure, Apple will always deserve a premium based on its stylish design, its innovative features, and the sheer bliss of the iTunes store itself. I get that. I'm not naive. I just believe it's dangerous to assume that a platform will rule forever when the market currents are flowing away from a closed ecosystem.

In short, I'll try to avoid putting a zero after Apple in the future. Just make sure you recognize that the same zero represents the chances of Apple never failing.

Other hits on the Amazon playlist:

Amazon.com and Yahoo! are active recommendations for readers of the Motley Fool Stock Advisor newsletter service. Wal-Mart is an Inside Value stock pick. What are you doing for the rest of October? Why not make it richer with a free 30-day trial subscription?

Longtime Fool contributor Rick Munarriz did kick the tires of Amazon's MP3 downloads last week, and he was surprised by how quick and easy it was to get a little Arcade Fire into his PC. He does not own shares in any of the companies in this story. He is part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.