I sort of agree with this and I sort of don't.
Yes, the giftedness can certainly cause some social difficulties. However, these can be exacerbated if they are not appropriately addressed. Imho, children still need to learn how to relate to their peers effectively, and that takes social skills which may not come naturally.
Of course, there may be differences in attention spans or topics of interest etc, but if children can be taught to navigate these differences effectively, their day to lives will be much easier and much happier.
I don't think it's simply the case that they want to play differently or talk about different things. It's partly about not having the skills to adjust what they want with what everyone else wants as well.
You often see parents of gifted children on these boards suggesting that, because their children are so clever , they can only relate to older kids/kids who are also gifted. Personally, I think it's far more likely that they simply haven't yet learned the social skills to manage interactions with people who are different from them effectively.
Kids with really good social skills, on the other hand - even incredibly gifted ones - are able to manage relationships with much less advanced children, and indeed, much younger children, far more effectively.
The thing that really bothers me about this is that many parents often fail to invest properly in developing the child's social skills, because they have bought into the idea that struggling socially just goes with the territory of being gifted and that's how it is - quite possibly reinforced by their own experience of struggling socially as a gifted child themselves. I don't think that belief system is helpful to the child, personally.