The change in discussion quality has occurred because old Twitter had an objective to cultivate one particular quality of discussion, and Musk Twitter has an objective to cultivate a different quality of discussion. These goals were stated up front by the respective decision makers. Any particular technique is simply a tool for the job. If old Twitter or new Twitter thought a method would aid in their quality cultivation goals, then they would have adopted it: if it proved counterproductive, then they would drop it.

So there is almost certainly a correlation to the boost that is given to comments. But even if it is a causative correlation, the ultimate cause is not the bluecheck boost, but the desire of the decisionmaker.