I think it's just got to do with the nature of the guitar, and the lack of formal education of guitarists. Here's what the search for an F5 chord brings up. If you notice, there's quite a few of them that make the same noise, but have completely different way of playing them. The way a guitar is set up, if you play an open string, you can make the exact same sound by playing the 5th fret (4th, on one of the strings) on the string below it. For example, to play the A note, you can either play the 5th fret on the E string, or just play the open A string; they both make the same sound (It's actually used as a rough method of tuning, called 5th Fret Tuning). That's where tableture comes in. Not only does it tell you what chord to play, it also tells you what fingering to use. This can be helpful for starting guitarists, because they aren't likely to really know what an F5 chord is by name, or different ways to play it. It also shows, usually, the easiest way to play a piece, because they will usually try to keep similar structure to make it easier to change from chord to chord. Sheet music really doesn't show this, unless it's specified in the writing (based on my limited knowledge of sheet music). Guitarists are taught tableture, not sheet music. If you learn a song online, it's in tab form. If you have a teacher, he's probably not going to give you sheet music. For people that don't have strong musical knowledge, it's a lot easier to connect with. With sheet music, you have to know how to read standard notation, as well as how to play what it's telling you. Tabs just say "put your fingers here" (however they don't usually give rhythm, but many already know the song, so they can figure it out), which is easier for beginners. Some eventually will learn how to do sheet music, but many just keep to tabs, because they're easier to them, and they're used to it. Also, I think this is relevant here.
I wanted lessons but my parents didn't set them up. I was 12 years old. I taught myself out of a chord book. I can't even read tab. But as a result I have a pretty damn good ear for figuring out songs. It was a fun way to learn. Now that I'm taking violin lessons with my daughter, I look forward to learning how to read.
I just started playing chords. Eventually someone gave me tablature. I just never had a reason to learn to read music for guitar. I can read sheet music for Cello and I can tell what each note is, I just don't know how to play it on the guitar :)
I'll tell you the real reason guitarists can't read music. They don't do it enough. Most guitarist get started with nothing or with tab and develop the skill to get by with poor reading skills. I was a jazz major for a year when I got out of high school, plenty of guitarist around who could site read just as people who played other instruments. If you've seen a twenty something guy sit down and do a decent first read of Eternal Triangle on guitar than you know it can be done.
I disagree. I learned piano as a kid, and then taught myself guitar as a teenager, so by the time I picked up a guitar I had already been sight reading on piano for 5+ years, and additionally I had very little access to guitar tabs at the time because this was before my family had internet access, so a lot of the material I learned early on was from piano-centric sources, typically sheet music, occasionally with some guitar chord charts thrown in. So if the problem is that too many guitarists are exposed to tabs first and then are too lazy to learn to read sheet music, I should be immune to it. I knew how to read sheet music before I ever touched a guitar, and from the start I was attempting to learn guitar by reading sheet music on it. Yet to this day, I find tabs far quicker and more intuitive to read than sheet music, when playing guitar. Even if I use a score that has both sheet music and tabs side-by-side, I find myself primarily relying on the tabs, and only glancing at the sheet music if I need a clarification on timing. Now I definitely agree with you that it's possible for a guitarist to learn to read sheet music quite well, but it takes a lot of work, far more so than what it takes for a pianist to learn it, and it's because of the issue mentioned in the article: sheet music notation maps nicely to the keyboard, but not the fretboard. That's why there are plenty of mediocre, amateur pianists out there who can sight read competently, and many excellent, sometimes even professional guitarists who struggle with it. The reason guitarists use tabs is because of the nature of the instrument, not the nature of the guitarists.