Why are you okay with the Rogue out of all classes lacking a combat-focused build?
All the other classes (to my knowledge) can be built for combat. Party-focused combat even (that is, disregarding the "the Rogue does perform well in combat, assuming it gets to sneak around on its own" argument).
Most complaints (that I've seen around here) are directed towards beastmaster ranger, four elements monk and sorcerer. But it turns out ranger multiclasses excellently with fighter, the beastmaster is the sole class WotC have conceded needs an upgrade, you can choose another monk subclass, and as long as you choose red draconic the sorcerer does splendidly (and in fact rises to the DPR top on any short adventure day, converting most low-level slots to sorcery points to twin or quicken spells or even both in the same round).
But the Rogue is expected to work its ass off, and for what? Byzantinely scrounging a second sneak out of it? That's not good enough - that level of play expertise plays off much better with any other class.
Even if I buy your numbers right off the bat, the thing is, no class as squishy as a Rogue will "dominate" combat with a mere 2 points advantage over the sturdy Fighter. What it does imo is just barely justify why any party would invite a rogue - sure it's squishy, but at least it now pulls its own weight (dealing competitive damage), and it's useful to bring along for hidden traps and treasure.
It is, after all, "just" a martial. Imo all martials need to do well in combat, since they don't have nearly the same amount of doodad magics as the full casters.
I think the fundamental conflict on that is opportunity cost. For any of the casters to have a high-damage combat build they generally have to give up a lot of their other options, this hurts less for the big three classes that can rechoose spells each day but still exists.
A bard who goes all-in on damage probably stops healing or inspiring teammates as much, using their dice and buff spells on themselves, and still won't be good at it compared to a real combat class.
A sorcerer is a bit more obvious because they have so little for features beyond spells. If they pick for combat focus they give up almost all of their potential utility out of combat, and are probably hosed if something is resistant or immune to fire.
The martial classes are limited because they don't have a big pool of features to pick from to determine their focus, it is chosen to a large extent at class selection.
A fighter is good at fighting because his base AND subclass features are all aimed toward combat, the same reason he is never going to be as useful outside of combat as a rogue, bard or ranger.
A rogue will often be a bit behind the fighter in straight-up combat because the out-of-combat part is baked into the base class features so you can't give those up for more fighting like you can in some other classes. Much like the bard they can't really go for a true 'combat build' because their utility comes from a part of the class you can't exchange for combat options.
Many people see this as a feature. Your class determines your outlook. A fighter will focus on main combat in some form. A rogue will be utility with a strong dose of (common) situational damage. A ranger will have more utility than a fighter (especially in the wilds) but will have fewer combat options.
Other perspectives see it as a bug, where all classes should have the option of ditching more of the utility aspect of their class to focus primarily on combat, instead of having the mix dictated by class choice. In this specific example it would probably involve ditching the skill focus of the rogue to up their combat gimmick of sneak attack.
I do suspect the Great Weapon Master feat in particular was built to help strength fighters and barbarians not get completely left behind by rogues and other DEX heavy builds shot got accuracy, damage, initiative, defense, and some useful skills from one stat.
I also think people really underestimate the potential impact of that -25% chance to hit that comes with those feats against less mookish opponents, but I have limited experience to say for sure so do not wish to imply it is anything but theory and a gut feeling.