It is more nuanced than that, but you've got the right idea.

Some years ago I tried the Zone Diet(TM), and was able to loose in the ballpark of 20 lbs. For the first month, all carb-rich food was strictly banned, and that did have physiological effects. Later, once the process had been kickstarted, non-junky carbs were gradually reintroduced with little effect on my pace of weight loss.

So... I tend to agree with you. People evolved to eat carbs, but not necessarily highly concentrated, processed carbs.