DCA certainly has benefits beyond return on investments. I believe it can be helpful to reduce anxiety by providing a simple investment routine and a sense of control. Furthermore, it can save time because there's no need to think about when to buy or when to sell.
As for monopsony-like effects, I don't disagree, but I'd appreciate more elaboration from the OP on why it's the case.
All I am saying in essence is that, while we may not even be aware when a monopsony-like effect begins to happen, it is to note however that the way power is concentrated in the mining pool of large exchanges, institutional investors probably acquiring ETFs and other large pocket investors may tend to create a situation that is monopsony-like, where there is but fewer persons who have significant control and influence over the cryptocurrency market trends by their acquisition of a particular crypto currency in larger volume than others.
That's why the DCA strategy from this approach is way important than any short term profit, so as to close the gap on control and influence that those who have more BTC in their portfolio than the rest, will have over the market.