Low level characters would never have a chance ever against higher level ones... Not even a small chance.
Yes. This is what I want and is actually how combat progression works in 5e. Skills in 5e are (very slowly) linear, whereas combat is exponential.
Combat and magical-ability wise, level 1 D&D 5e characters are novices. Better than the average commoner, sure, but not overwhelmingly better. Easily defeatable by a goblin. Level 20 characters, however, are practically gods. Due to bounded accuracy, a goblin could still possibly hit their AC. But due to ~unbounded abilities and HP, low-level characters&monsters don't stand a chance.
However, when you look at skills (and STs), the differences are comparatively miniscule. A level 20 adventurer is only ~35% more likely to succeed on the same check than a level 1 adventurer with the same skill proficiency. Which is about the same difference between a level 1 adventurer and a (unskilled) commoner.
There are loads of good things about bounded accuracy. It vastly simplifies the game which has certainly helped with 5e's popularity. But personally, I'd rather a bit more complexity and level 1 adventurers being unable to succeed on certain things (e.g., DC 30 lockpicking/acrobatics/perception) that higher-level characters can do with ease. To bring it back to the thread's topic, I'd be fine if Larian took some liberties with this.
p.s. Regarding Advantage: with my system of skill advancement DCs would be increased, so Advantage should have a similar effect as currently, though it would obviously help less if you're completely unskilled. But theoretically you could still Help an ally, giving them Advantage!
