The problem with sugar is, IMO, glycemic index. With glucose being an index of 100, no sugar being an index of 0, and something that takes a moderate amount of time to convert from starches/etc to sugar being 50, things that are higher than 50-60 tend to spike your blood sugar and cause insulin to scavenge the sugar out and store it in fat. Doing that often causes things like insulin resistance and obesity as you get hungry again when your blood sugar drops.

Fruits have a surprisingly low glycemic index because they aren't processed and you have to get through fiber and digest the cells before having access to all of the sugar. I've changed my diet to avoid sugar and notice that I very rarely feel actively hungry/crashy vs. before, and most fruit is just fine.

http://www.glycemicedge.com/glycemic-index-chart/

Sure, that is naturally occuring, and I wouldn't advise eating too much of it either, but at least the ratio is offset by a lot of fiber (and water), so you get somewhat full.

But I get your point, it shouldn't really be about what's naturally occuring, but how it affects your body. I stay away from fruit as well.