I don't think is true, at least not in 5e (you could MAYBE say something like that about 3e or 4e, but I don't play these much nowadays; if you want a combat-focused game, try Mythras).
[BTW, you can tell that I mean it by the number of posts about combat in this blog - more weapons, more maneuvers, more options, etc.]
Look at the PHB: the combat chapter is quite small. The list of weapons is very short and, dare I say, underwhelming. Many races and classes have powers that are related to investigation or interaction (darkvision, languages, etc). "Martial" classes without spells are rare.
The DMG has a few extra combat options, but also honor, sanity, etc. It has plenty of magic weapon, though; see below.
The MM monsters are a bit more combat focused, but they have plenty of lore, art, and non-combat aspects (alignment, languages, some skills, etc). Although I DO agree that encountering monsters is a bit too combat focused in this edition, for the lack of reaction rules and similar mechanics.
D&D's pillars are, supposedly, combat, exploration and interaction, which is a fair thing to say (I might add "character development" but that's another story).
Another thing D&D is about is MAGIC. It takes the biggest chapters, we get more spells with every splat (not a dozen new melee weapons IIRC, two or three new combat styles, but 200 new spells since the core books, or something).
In fact, if we want more tools for combat, we don't get many alternate rules for combat, but more combat spells (and magic weapons).
Maybe you can say that D&D is mostly about magic, or even magical combat... But ordinary combat?
Take another look. There are no details about the interaction between weapons and armor. Only one type of shield. No reason to use a (non-magic) mace RAW. No specific ways of hitting a specific body part. Grappling is very simple. Disarming is an optional rule. This is NOT a game with an exaggerated focus on combat.
I've played many RPGs in which combat was downplayed (say, Call of Cthulhu or Unknown Armies); D&D is certainly combat-focused when compared to those. But it is unfair to say D&D 5e is much more focused on combat than, say, GURPS, Mythras, Pendragon, or even Castle Falkenstein (which has some pretty specific dueling rules). I won't even go into Riddle of Steel, Dark Souls (I don't even know if the RPG I read is official, but...) or other games that ARE much more focused on combat.
Maybe you can think RPGs in general are too focused on combat. It is a matter of taste. Maybe you think videogames are too focused on combat. Might well be. But if you frame it as a criticism to D&D, specifically, it is inaccurate IMO.
I feel the same in practice (although that's anecdotal evidence): we spend only a fraction of our 5e games doing combat, and in my last CoS session there was no combat at all. My experience is not universal, but it is one example on how you can play D&D without focusing on combat.
I posted something similar over reddit and got massive criticism. Still, I believe readers of my blog will have a better understanding of this issue.
BTW, there is more 5e-combat-oriented stuff coming soon!