I see what you're saying. That is one way to look at it. From my own perspective, I would amend that statement: The game has a stronger emphasis on combat, but the DMs can influence the play for their games. So without DM guidance or influence, a player looking just at the rules might assume that combat has the lion's share of the attention, and he would not be wrong. Rules are just rules. But the beauty of RPGs is the rules are just tools to be used as needed. Thus a campaign with heavy social interactions would make less use of the combat rules, which make up the majority of the game. That doesn't make it greater or better. It's just the way it is. DMs should inform their players what to expect as many will just assume combat will be in the cards regularly.
I definitely agree that no way is greater or better than another. As long as the group is having fun, that's really the only thing that matters.
This is what I am seeing. Let me try to explain it in more detail. When it comes to beginning some exploration, all you really needs is for the players to let you know that they are going down the steps into the tomb. When you begin a social interaction, all you really need is for the players to let you know that they are walking up to the bar to ask the barkeep if he has seen the mysterious stranger. When you begin a combat, you need rules for surprise, distance, movement, perception, and initiative. Then you need to know how to attack, what attacks there are(grapple, tripping, disarming, etc.), rules for damage, hitting, unconsciousness, and much more.
Once you're done with that whole combat section, you need to come up with mechanics for all three pillars for the various classes, and again combat surges ahead due to the complexity. You not only have the combat abilities in the classes themselves, but dozens of pages of spells for the various spellcasting classes. On the other hand, for exploration you just need a few rules on skill checks and some skills. The same for the social pillar.
That's why the game has the vast majority of the mechanical rules in it relate to combat. I think the default assumption is that the pillars will be roughly equal. I think the game expects that you will be invited to the King's banquet and shmooze socially with him and the other nobles for a while(a third of the night), then after you go to your rooms you sneak out and begin exploring to find the way to the vault to steal the crown jewels(a third of the night), and lastly when in the vault some guards burst in and you get into a fight to escape with the bounty(a third of the night).
Again, I agree that it doesn't have to be that way and you can have any weighting of those pillars the players are going to enjoy. There's no wrong way to do this as long as you are having fun. However, I don't think that the rules intend for combat to be the primary of the three pillars. I can also see how a new player flipping through the rules could get the wrong impression of what the game intends to happen.
The DMG also seems to agree with what I am seeing. When it comes to designing adventures it tells you to get to know your players and give them what's interesting. Fighting is just one of seven categories with no particular emphasis on it over any of the others. And the creating adventures section tells you to blend social, exploration and combat into a unified whole, also with no particular emphasis on any one pillar.