I don't know about this one, I've seen the argument that there are fighter builds that out strike the Warlock and Rogue in pure damage capability. Also as more classes come out it does seem as if more overlap is almost inevitable, and finally unless strict balance is always maintained... classes in the same role may have varying levels of effectiveness...like the Invoker who is held up as an example of a better "controller" than the Wizard.
From what I've seen, those fighter builds all were based upon the assumption that the DM would provoke opportunity attacks from the Fighter in a rather nonsensical manner. Additionally, too many people forget that being a striker isn't only about dealing damage (because if that were the case every class would be a striker). It's also about having the mobility to
strike behind the enemy front-line in order to destroy dangerous but squishy targets (like artillery).
The designers have already admitted that they borked the Wizard's design a little. Presumably, next month's Arcane Power will help to remedy the situation. A better comparison would have been the Invoker vs the Druid.
But if you can build an encounter that favors certain roles... doesn't this fall in favor of the spotlight being just as dependent upon the DM as any earlier edition?
No, because the advice in the DMG tells you how to avoid doing that (you can reverse engineer it though; no system with a human component is foolproof after all). As long as you follow the advice in the DMG for building balanced encounters (which really is very simple) the system takes care of the rest. The Wizard can't cast a few spells to suddenly take over the Defender's role, for example, so the DM doesn't have to worry protecting the Fighter's "defender-hood". Admittedly, many people claim that this did not happen in previous editions, but a significant number have claimed that it did, so it is pertinent (since it suggests that this affected some significant percentage of groups out there).
And here I totally disagree, much as people claim that niches are preserved in 4e, I think it's easy for a character to step on another's toes if their niche isn't based in combat. A Ranger can easily out thief a Rogue... in fact as long as a class has an attribute focus that coincides with the attribute for the skill(s), it's trivial to spend a feat and usurp a skill-based role in 4e especially with Backgrounds, skill focus, skill training etc. being optional ways to surpass another PC.
I think you are exaggerating the ease with which a Ranger can out thief the Rogue. For starters, this is only even pertinent to a subset of Rangers (since melee Rangers are Str based). Secondly, he is spending
at least one more feat than the rogue to accomplish this (to train Thievery, which rogues get automatically), which means that that Rogue is now a better striker (assuming the Rogue spends this extra feat to improve his striker damage rather than expand his options). Finally, Rogues can select powers that assure the Ranger will never be his equal (PHB pg 119, Fleeting Ghost and Quick Fingers).
Can a Ranger who focuses on being a thief be a better thief than a Rogue who neglects that aspect of his character? Absolutely. Does this demonstrate a lack of Spotlight Balance? I say no, because the Rogue who wants to be a master thief will always be a step or two ahead of any Ranger "competition". Just because a Ranger who wants to be a competent thief can be, doesn't make the Rogue any less special.
Yeah, I'm just not seeing this conclusion at all... spotlight balance, especially with skill challenges and the ease with which one can raise skills (which may or may not conceptually have anything to do with your niche) to high levels, IMO, do much to disprove this conclusion.
IMO, this is simply an indication that they were unwilling to craft a system tyrannized by Conceptual Balance, but rather used a somewhat more balanced approach. Want a Ranger who is good at thieving? Feasible. However, the Rogue who focuses on combat will be a more effective Striker, and one who focuses on thieving will always have an edge on you in that department.
Which, in turn, suggests that flexibility of character creation has not been utterly sacrificed to the gawds of Conceptual Balance after all.