Wow. I mean I wish I could rate posts. I'd give you 5 stars. That was helpful, and that article really captured some of my EXACT thoughts and experiences. I have a light camera, Canon SL1, but heavy lenses, Sigma 35mm f/1.4 and Canon L 85mm f/1.2. Might as well save up for the Gitzo. Maybe I will get something inexpensive from Craigs or evilbay to tide me over till I can drop the cash on a good one.
It all depends on your needs and what you're shooting. A basic tripod would probably be fine for, say, a wedding photographer. Most of the time the tripod is simply acting as a stand for your camera. You're lining up groups of folks, go and check the framing, could you move to the left ma'am, ok, snap, we're done, thanks folks. Super precision and stability are not 100% needed. There are plenty of wedding photogs who do it without a tripod entirely. It all depends on your lighting situation, of course.
But say you're doing landscape photography, you're going for ultimate image quality, you're shooting at ISO 100, f/11, CPL filter and maybe some ND filters on top of that, you want to photograph streams and waterfalls in the deep shaded woods at 1+ second exposures. That's when your need for more precision comes in, not to mention light weight.
It also comes in when you're doing macro photography. You're dealing with DOF in the sub-millimeter range, you position your subject very carefully, make all the adjustments on your tripod to get it at the right height and whatnot, and then step in to make the final adjustments to position the camera precisely for the framing desired. You clamp everything down and... shit. It moved down slightly. The top edge of your subject is cut off. Now you un-clamp the ballhead, trying to hold it the right amount UP from where it was before, so that when you clamp it down again, it will move down to where you actually want it. A frustrating experience.
I guess it's buried as an assumption in this discussion, but I'd like to make it explicit: the more telephoto you're shooting, the more obvious and painful these little nudges/weaknesses will be. If you're shooting an ultrawide-angle lens with a 90 degree angle of view, a 1/2-degree shift in your framing isn't going to make a difference. But if you're shooting a 300mm lens with a 7 degree angle of view, a 1/2-degree shift is a substantial portion of your framing. Not to mention, the 300mm lens is more likely to have this effect on your tripod and head since it's probably a lot heavier and a lot longer than the UWA.
Basically, take any discussion involving shutter speed, how much shakiness is acceptable, etc. and apply it to the tripod discussion.
Also, note that durability is definitely part of the expensive tripod equation. Durability vs. cost in particular. A lot of the cheap/lightweight aluminum tripods will get bent and dented fairly quickly if you don't baby them. This can affect functionality. My 3021 is aluminum, but thick tubular aluminum.... like 1/2" aluminum pipes with nice thick walls. I would not hesitate to hang my weight off of it in an emergency. But it is quite heavy, so it doesn't really go anywhere that my car doesn't go. It is perfectly fine for most of my uses, however; and if you were really into, say, indoors macro photography or other studio uses, you probably wouldn't need any better. The carbon fiber legs are good at being durably strong for their weight.
Also, as others in this thread have mentioned, technique can get you lots of places. Hanging a heavy weight from the tripod (directly underneath the camera) can add stability and dampen vibrations in high winds. Setting up the legs at the correct angles for the terrain is another aspect.
Also, note that that article was first written in 2003. At that time, carbon fiber was a lot more expensive. I doubt the author has done a lot of searching to find lower-priced alternatives to Gitzo legs since he already had them. I have heard good things about lower-priced CF legs, I can't remember the brand name, but I think there are some out there that cost roughly half of the comparable Gitzos and are still pretty good. So there are definitely more options out there than he mentions, but Gitzo is still pretty much the top dog AFAIK.