It's popular because people think it's a helpful point to make. Nonserious people can and should become serious. And science shouldn't be a LARP.

I was a professional scientist (in cognitive psychology and neuroscience) for two decades and change. I quit largely because the field wasn't serious in this sense. Nobody cared much about applications. They were just enjoying "doing science" (or sometimes not even really enjoying it).

They damned well could and should get off their intellectual asses and become serious. That's what this post advocates, and it's very much a matter of choice and perspective. That's why it's perceived by many, including me, as a valuable point and perspective.

For me, I felt like publishing in scientific journals required me to be dishonest.

...what?

I can't speak to what the OP meant by that. But scientific publishing does require spin, at least if you are aiming for a good journal. There is not some magic axis by which people care about some things and not about others, so its your job as an author to persuade people to care about your results. This shifts the dial in all sorts of little ways. 

"Well, in the end it seems like we learned nothing." If that is the conclusion you don't get to publish the paper, which is not good for your career. Where-as "In conclusion, we have shown {really important result} beyond any shadow of a doubt" is good. But real results are in the middle. You have something, but there are caveats, assumptions, details that you don't think are important but who knows maybe they are? On any particular weakness, how much emphasis does it get? A paragraph? A sentence? A footnote? In the supplementary information? Entirely missing? How much emphasis would you give that weakness in your methodology if the publishing process was not incentivising you to put it as far down that list as possible? 

The manufacturing process was not reliable, but the 32nd device tested worked fairly well, as plotted in fig.3.
"Why mention the 31 devices that the paper is not about?"

Assumption 1, assumption 2....
"Its nice that you understand and explain these assumptions so well. But they are all pretty standard in the field. I think we can drop these paragraphs, just say "using standard approximations", actually "standard methods" sounds better."
 

The end result:

PhD student's draft: "It is possible that quantum information technology might be important at some point in the future. One aspect of that is 2-bit operations, but they need to be robust. One particular 2 bit operation is the CNOT gate. In this paper we demonstrate a CNOT quantum gate, that only worked on the 32nd tested device. Its nowhere near good enough for a useful quantum computer, but it  worked OK on Tuesday, which is something (when I returned to get more data on Wednesday it had permanently stopped working for inexplicable reasons.)."

Final (published) paper after the professor has had an edit: "Quantum technology will soon revolutionise all aspects of human society, bringing vast social and economic benefits. The key obstacle to realising these enormous gains is a reliable the 2-bit quantum gate. In this paper we propose a novel design for such a gate, and find that a high level of reliability can be achieved simultaneously with improving the device's speed."

Have you met non-serious people who long to be serious?

I am one of those people—modulo some possible definitional skew, of course, especially around to what degree someone who wishes to be different from how they are can be considered to wish for it coherently.

I know that right now I am not acting seriously almost at all, and I feel a strong dislike of this condition. Most of my consciously held desires are oriented in the direction of seriousness. A great deal of me longs to be serious in wholeness, but that desire is also being opposed by a combination of deep (but ego-dystonic) conditioning, some other murkier limitations that seem ambiguously biological and in any case have been very difficult to get at or pin down, and some major internal conflicts around which path to be serious about—whose resolution in turn is being obstructed by the rest of it.

Edited to add: to be clear, this isn't a statement about whether the article winds up actually being useful for helping people become more serious, and indeed I have a vague intuition that most reading-actions applied to articles of this general nature may decay into traps of a “not getting out of the car” variety. (If I had a better way that I thought would be useful to talk about, I'd be talking about it.)

"Have you met non-serious people who long to be serious? People like that seem very rare to me."
… Hmmm… kinda? Like, you’re probably right that it’s few people, and in specific circumstances, but I know some people who are doing something they don’t like, or who are doing something they like but struggling with motivation or whatever for other reasons, and certainly seem to wish they were more serious (or people who did in fact change careers or whatever and are now basically as serious as Mastroianni wants them to be, when they weren’t at all before). But those are basically people who were always inclined to be serious but were prevented from doing so by their circumstances, so you have a point, of course.