Remathilis
Legend
Yes, if you pick two characters of the same role and pick similar powers you will have a similar play experience.
From what you've stated, I'm guessing your Warlord used Furious Smash a lot. I'd also guess that your Artificer used Aggravating Force and/or Magic Weapon quite a bit.
I imagine you'd have had a very different experience if you'd first played a Warlord and then a Warlock (which play nothing alike) or even if your Warlord had focused on movement influence (Viper's Strike and Wolf Pack Tactics) while your Artificer used a buff/debuff combo (Aggravating Force and Static Shock).
No offense, but your argument sounds to me as if, in 3.x for example, you were to say that the Sorcerer and Wizard were identical because you played a character of each class and focused both on fire spells. If you build two characters with the same role using similar choices, then yes they will be similar.
FWIW: Warlord: Furious Smash and Viper Strike. Artificer: Static Shock and Magic Weapon. In both cases, I found FS and SS vastly more useful than the other power. Same went for my wiz/inv friend who found magic-missile and Sun Strike so useful (and similar) he called one the other.
But doesn't that beg the question: If playing a leader isn't going to feel all the different from one another; why make a big deal about it. I recall arguing with another friend about druids-as-healers and why they sucked at the role (sure they got cures wounds, but at the cost of much better druid spells) and how 4e was going to fix it.
They did. They made sure every leader was good at healing by giving him the exact same healing power with a few changes (add 1d6! add your cha! add both!) and a different name. While it might be fun to say "I'm a cleric! I'm warlord! We're totally different people!" Wouldn't it be interesting to have a leader that grants fast healing? Or one who actually create little potions of healing (set at his healing surge) that character can carry around? (rather than a nonsensical you blow magic smoke at an ally or however Curative Admixture works) What about the idea that, ya know, SHOUTING at a guy to get up isn't as effective as CALLING ON YOUR GOD to heal him?
Or how bout an illusionist that creates illusions, not just deals psychic damage (like a fire mage deals fire damage) and give him a -2 to hit. Why can my illusionist make an illusion of a foe falling through space and time, but not an illusion of a door?
Perhaps some of those classes would be too powerful, or others would fall into accidental suck. All I know is that at least when I run my artificer, I wouldn't feel like someone gave my warlord a wand of magic missiles and told him to stand in the back, they'd play and feel different in their role.
One last note: Even if you built a sorc and wiz around the same spell selection, their would still be play differences. The wizard would have to be more cautious with his spells (because he has less of them per day) and might rely more heavily on wands and scrolls (esp for lesser-needed spells) while the sorcerer having many more spells per day is going to be a bit more free with using them and probably invest in metamagic to expand his spell options rather than item creation. Sure, you'll still be in the back casting spells, but the two would have a lot less in common. (This is EXTRA true if the casters didn't focus on the same spells; a sorcerer obsessed with polymorph feels very different than a necromancer-wizard. Try either of those characters in 4e.)