To my mind, that "not balanced and swingy" option would be:
- Characters always roll their ability scores, with no "Mulligans."
- Characters always roll for hit points, even at 1st level, again no "Mulligans."
- Character classes all have different XP advancement tables, spell progressions, hit dice, and proficiencies, and they get different abilities at different levels. Some classes would end up being innately better at some things than others.
- Same for species: some get ASIs or feats, others get innate spells, and they aren't really coordinated with others. Some species choices are innately better than others for certain types of characters.
- Weapons all do different amounts of damage. Some have many additional properties and features, others have none, and there is a lot of overlap and duplication.
- Spells and cantrips: see "Weapons," above.
The thing is: this is pretty much how the older editions of D&D were played. Heck, I remember rolling ability scores
in order, such that you didn't even know what character class you were going to end up playing! Everyone wanted to be an elf, too, because they were clearly superior for all but a small niche of character tropes. One failed save throw and you were dead--do not pass Waterdeep, do not collect 200gp.
This style of play has all but gone extinct in the 40 years since. It looks so strange nowadays when you write it out.
While 5E is a far cry from "perfectly balanced and linear," it did flatten a
huge amount of stuff.
- Characters all start with the same six ability scores. Remember the Elite Array of 3E? Nowadays we have Point Buy, which is only slightly different.
- Characters all start with max hit points, and can choose an average roll at each level-up. The exact number of hit points still varies by class and Constitution score, but it's much more flat.
- Character classes all have the same XP advancement tables, and most of the spellcasting ones use the same spell progressions. Most classes get their features at the same levels. There's a lot of argument about whether some classes are innately better than others in certain situations (are wizards are just as effective in ranged combat as rangers? should they be?) but these differences are becoming less distinct.
- Most species start with the same ASIs and with the same features (like darkvision and bonus proficiencies). This is especially true for the most recent character creation rules, in Tasha's Cauldron of Everything. There are some species that can breathe underwater or fly, sure, but they're as uncommon as they are controversial. For most tables, no species is going to be innately better than any other.
Again, 5E is not "perfectly balanced and linear." Weapons, feats, and spells are all over the place, and are the source of most of the "randomness" and "imbalance" that I read about here on ENWorld. (Add multiclassing into the mix and
hoo boy.) But when you step back for a minute and look at how the game has changed over the last four decades, you can see how the game has moved away from that wild, unpredictable randomness.
I'm not saying this is a good thing, I'm not saying this is a bad thing. I'm just saying that it is definitely a thing.
Define 'linear and predictable'.
Excellent point. If you take this all the way to its most extreme, you would end up with just one character class, one single species, with the same ability scores and hit points, and the same decision tree at every level-up. All characters would be different in description and flavor only. And you're basically playing Skyrim, on a tabletop. I'd probably still play it, but...meh.