My thoughts are this:

If it's something that I am going to be dealing with on a recurrent basis, then it is worthy of a diagnosis. There are good times, and there are bad times. It doesn't disappear, I'm just not symptomatic all the time and hence I spend a chunk of time baseline. I have depressive episodes and I have hypomanic episodes. Those are their names, and together they form bipolar disorder.

I don't think that the diagnosis is destructive. The point of having a diagnosis is to be able to explain the general symptoms of what is going on. What is destructive is people who either A) think that it's all faked and that you're not actually ill or B) people who think that you can not function in life.

If people would get past all the stigma, then there would be no destruction caused by saying "I have bipolar disorder."

So really... the destructive part is people's ignorance. Which they will never overcome if the diagnostic labels are not used.