To answer a question like this, try looking for examples of works that have both balance and a focal point. These do not have to be web pages, and in fact it may be easier to think of these ideas outside the context of web design.
Consider this photograph:
This clearly has a focal point: the bright green center of the Kiwi fruit. But it also displays a serene overall balance.
An even simpler example is the photo below, which is completely balanced, with the focal point in the center:
The painting below also clearly shows both focal point and balance in one work:
And here is one more example:
So focal point and balance can and often do go together, particularly when the composition is symmetrical. But there could also be cases where your idea that focal point unbalances a composition is also true. For example, this Degas painting has an obvious focal point, but whether it is balanced or not is debatable:
One might classify this composition as "unbalanced," if one thinks the focal point has weight that is not really matched by anything else. Or one might argue that the balance is more subtle, with the expanse of floor itself as a counterweight.
I expect that these and similar observations based on art can be applied to questions of balance and focal point in web design too. Hope this inspires a few good insights.