spalco said:
Again, look at the people who managed to do it. It's great company to be in.
It sure is, but it's also something that anyone who won three Tours or two Tours and a Giro would have been easily capable of. The main reason it hasn't been done more often is simply that for much of its history the best GC riders didn't ride the Vuelta seriously. If you can win the Tour, you can win the Giro and if you can win the Giro, you can with the Vuelta.
The Triple Crown though, that's a different kettle of fish. It takes a different set of abilities above and beyond those needed to win a grand tour: You need to be able to win a top level one day race and, crucially, you need to be able to show the form necessary to win a grand tour twice in close succession. Most Grand Tour winners simply can't do that.
Getting the full set of the monuments is a different thing again. There are so many things you have to be amongst the very best at.
I think you'd have difficulty finding a pro, past or present, who would take a Tour, a Giro and a Vuelta over three Tours. And that should put the importance of that achievement into context.