Sure. I don't think lumping D&D and the other games I was thinking of together is particularly useful, but if you want to accuse me of thinking in a relatively trad paradigm in these posts I'll plead guilty. However I'll disagree that Cortex+ is going to automatically answer the question if its not designed upfront specifically to do it; there's nothing about Cortex that automatically avoids the same kind of failure states most other games tend to with stealth.
In the Cortex Plus/Prime paradigm, there are no difficulty modifiers.
it's all opposed rolls, based upon already established ratings, and a very limited set, at that.
The exact details of building a pool vary across different CP/P games... but I'll give two examples:
MHRP: One distinction (d4 hinder or d8 help), Affiliation (d6 d8 or d10 by character), One power from each power group the character has (from 1d6 to 1d12 for the power, and 1 to 3 groups, usually 1), one Expertise (aka skill, d6/d8/d10/d12), one signature asset (if you have one, d6 or d8), one temporary asset for the character (d6), one for the scene (d4-d12 if applicable), one opposition damage complication.
Firefly: One distinction (as above), one attribute (d6-d10), one skill (1d4 =unskilled, to 1d12), one specialization of that skill (if applicable, 1d6), one signature asset (1d6 or 1d8, if applicable), one temporary asset (d6, usually), one scene asset (if any, at it's rating d4 to d12), one opponent complication (if any and relevant, d4 to d12)...
Assemble to the pool, roll it, set aside the 1's, pick 2 of the rest for the success calculation, and one of the non-1's for the effect (which is a complication or asset of the same nuber of sides as the effect die). 1's can be converted to plot points and
Fate, likewise, it's all either opponent's skill, or how hard should it be for joe average... and whether you can apply aspects. As written, no adjustments for situation unless they've been codified into assets. And doing so requires a skill roll or a fate point, or both...
2d20 can be run in this mode, too... but it's not the default mode for most 2d20 games.
The fundamentals of many games of that style are highly mechanical but not subject to a lot of rule searching; for the GM's calls on their character's labels on aspects/assets or Powers, it's simple enough to have a hand signal of disagreement when the dice are pushed forward during the narration. (and for Cortex, I don't have players FTF announce the dice, just narrate and point to the level as the put the die into a dice cup or onto the character sheet. (On the sheet works GREAT for Marvel Heroic... since I blow the sheet up from trade (6×9 inch) to letter (8.5×11 inch)...)
And then, there are the AWE/PBTA, where most don't have difficulties at all - it's roll and add skill, and check on the universal range...
Keep in mind also, I'm prone to old school as a minis wargame with interludes; so for me, these games do force me out of that mode, and out of the simulationism I used to enjoy.