Just to generally address the people that seem to discourage and/or dislike multiclassing: Why are you trying to bend to your will a system based so heavily on building your character via multiclassing and mechanics to represent fluff?
a) I don't dislike mutliclassing nor do I try to discourage it. I have rules that discourage multiclassing into more than 3 or 4 classes, and I have designed my system to only need 12 or so broad base classes total, but multiclassing is encouraged. In my current campaign I have 6 PC's and at 3rd level 2 of the 6 are already multiclassed, and a third is thinking about it.
b) I don't mind building up a character's abilities with mechanics or using mechanics to give a character a particular schtick. What I object to is the idea of continually adding inflexible chunky PrC's as the means to get there. What that really suggests to me is that either there aren't enough feats or class ability customization to obtain the concept (and that may require me bringing in a discussion of how many feats are 'enough'), or that the feats required to obtain the concept don't exist or are poorly designed, or that the base class is unnecessarily narrow and inflexible.
Why not just try to play older versions where your only options were a single multiclass or dualclassing?
The question is too broad to answer in a reasonable amount of time.
I have to agree with Dandu's points about Fistbeard Beardfist, what's wrong with representing a character with what he can do?
Nothing. My problem with Fistbeard Beardfist was what he represented, and not that he had mechanics that fit his abilities. My problem with the system is that it requires the player to dip 6 different classes to obtain "barehanded brawler" (assuming that you wish the system to allow for barehanded brawler). I think the example is a poor one because it illustrates two separate problems, and I have probably been focusing on the wrong one. Let's assume however I love the concept, the problem remains is the hoops the player had to jump through to get there. Why is all that crazy dipping necessary? Why do we need 400 PrC's? If we want monks in our game, why do we need to have a PrC like Kensai or something that makes monks a (somewhat) viable concept? Why can't 'monk' itself be a viable concept?
A slightly more technical problem is mechanical variation for its own sake. Most of the abilities that Fistbeard Beardfist aren't technically essential to his concept, they are simply synergistic mechanics that give some mechanical advantage - like making his Constitution a god-stat that serves for almost every purpose so that maxing out constitution alone gives near universal benefit. That's not an essential component of the character. That's a particular mechanical implementation of the concept. Sometimes players mistake the particular mechanics of their concept for the concept itself. For example, getting AC from constitution is a particular implementation of 'tough'. But its purely arbitrary whether AC from constitution or DR from constitution or extra hit points from constitution above the normal is the 'right' implementation of 'tough'. The point is that the player needs some mechanical marker that means 'not just tough, but extra tough'. What PrC's from different splatbooks tend to do after a while is give every variation on 'not just tough, but extra tough', leading players to dip for every variation. This is like having a class based system that picks up all the problems of a point buy system. You've now got all the lack of character breadth combined with the more limited flexibility of class based.
Sure, some players like that sort of system mastery and mechanical variation for its own sake, but its one of the primary reasons that 3.5 got unworkably unbalanced in the long run. The way 3.5 was set up, you couldn't add more variation to the system (more viable concepts) without as a side effect incidently breaking things in combination with existing things. And that's to say nothing of the initimidation that such a system brings to a new player, both in terms of rules understanding and the economic burden of buying up all those splatbooks.
And ultimately, I think the designers of 3.5 knew that it was bad for the game as whole, but knew also that it was a profitable economic model to continue to provide endless mechanical variation on themes spread all over the place.
After all, when you introduce yourself to people you would identify yourself by your job title or as a practitioner of some hobby rather than giving them a complete breakdown of your psychological motivations.
I might, but its worth pointing out that I'm not my job title or my hobby and the reason that I would tell you what I do but not who I am would be precisely so that I wouldn't want you to know who I am until I'd established I could trust you.
Are you saying that you wouldn't let a player play a Rogue 10/Sorcerer 10 because at level 1 he cannot have abilities of both classes, therfore his development could not possible encompass such a combination?
To begin with, if a character wanted to play say a 'Gutter Mage' that was equal parts rog and sorcerer, he'd start out as a 0th/0th level apprentice type character using the 3.0 rules for multiclassing 0th level characters. He'd probably also start out with the Unusual Background (Gutter Mage) to make skills synergize better. And then, he'd probably start up the 'Interdisciplinary Student' feat tree to ensure that he didn't sacrifice his spellcasting ability too much, given that a rog10/sor10 is a pretty suboptimal build without some help.
And secondly, that's not what I'm saying. I'm saying that a second level ranger contains none of what is apparantly considered the essential aspects of 'Fistbeard Beardfist'. Most of his mechanics that will define him are well into his future. That's all well and good if you are starting out with 10th or 12th level characters, but it shouldn't have to take you to 10th or 12th level and 6 class dips to have your schtick in place.
Essentially you are saying that a character must have the exact same attitude at level 1 that he will have at level 20. Do you refuse your players the chance to allow their characters to grow and change?
Whoa there. I believe you are confusing emotional growth with mechanical or skill growth. Characters certainly grow and change in my game, and in an ideal world most of that growth and change isn't reflected in merely increased combat ability.
What about this for his Ranger 1 backstory? I'm a Ranger, my life was destroyed by my excessive alcohol consumption, so I took on a mantle of asceticism to try and control myself. I learned the ways of the Monks, their discipline through martial arts. Eventually I learned to embrace my vice as a source of power, rather than a weakness.
Forestory. At the time he's a Ranger 1, his Monk career is still in his future.