Nothing wrong with using dektol. It certainly rates being called the "standard" developer. But there is lot of variety out there. I think as people branch out in photography, they try different things to see if they work better than what they are currently using. In my case, I started seeing threads about Agfa Neutol WA giving results similar to Amidol. I tried it and found that it indeed gave better highligts and highlight seperation than dektol or the combination of selectol soft and dektol. At the same time, I explored Amidol and confirmed to myself all the good things that had been said about it.
Now my practice is to do my proofing with Neutol, saving the relatively expensive Amidol for the final prints. Still have a gallon of dektol setting on the shelf just in case.