So what, indeed. I was responding to your point about single-classed characters being better than multi-classed characters, as a justification for why multi-classing should suck for spellcasters.
Not better, just better within their specialty.
The specialty of a fighter isn't fighting- lots of classes fight.
Their specialty is having buttloads of feats that make a particular syle of fighting better, all while wearing any kind of armor they want. They are combat generalists.
Barbarian's specialty is Raging and being a formidable combat monster while being lightly armored. Plus some Nature-y stuff.
Whether multiclassing makes you a better combatant or not depends on a lot of factors. For instance, the assertion that Barbarian/Fighter is always better simply isn't true: if you want an archer build, levels in Brb are not going to help you all that much for optimizing the build.
I agree. So why should a wizard/cleric concept be party deadweight, again?
1) My Geomancer would like to talk to you about being called deadweight.
2) The saying "jack of all trades, master of none" sprngs to mind. The costs of learning a valuable skill is always going to include the opportunity costs of not learning another skill. I'm an attorney and an MBA with some not insignificant skills in the arts. Had I made different choices, someone might be buying a ticket to my concert or pirating my music right now.
In a free multiclassing system- one without meaningful tradeoffs- not only would I be a lawyer and MBA, but a guitarist, jeweler, sculptor, painter and who knows, oceanographer and malacologist as well.