Why not?
I see this advice repeated quite often on the forum and it leaves me scratching my head a little. Is this said to mostly protect players who aren't normally very 'gamer savvy' type of people? If so then I can understand that. But when this advice is given from a loot point of view I often see it alongside advice to take a pure class to 20 first...
... but that makes no sense to me. After all, as a new learning player would this not end up being more work than just going straight for a build that you are smart enough not to wreck? Seems to be it would be far more efficient to farm for loot on the character who needs it then it would be to have to level 2 characters vs. one.
Is it tomes? Assuming I'm willing to just buy the +1 tomes from the Store, then what is stopping me from farming for +2 tomes on my main character later on instead of some kind of "practice pre-character-character"?
I've never seen the logic in advising people to sink 20 levels of time in some type of "warm up practice character" as if it were a good idea to make that kind of time investment only to just shove the poor gimpy guy on a shelf while you play your "for real this time, this is not a drill" character.
Like I said, if this is intended to protect people who aren't really into powergaming or researching game mechanics from frustration, then ok, I can understand that.