There is this thing that people write in their posts as a disadvantage of blockchain. You wrote it in your post. Let me say it the way I understand it.
Blockchain is not same as cryptocurrency. It does have a value tag that is volatile like cryptos. So I do not think fluctuation is possible with blockchain technology.

The only thing one can say is that it doesn't work with the same level of efficiency all the time because of the number of users that differs at each point in time.