Edit: Adding this as a PSA in case folks start debating the veracity assuming this has undergone review by experts.
If they actually wrote their contribution in clear terms they couldn't get it published because it sounds too simple. I think they should be able able to get it published without inflating it's complexity like this. They are just reacting to a broken system.
In general, I am also not fond of this writing style. However, if one reads more papers published in this community/area, then one notices that many of them are written similarly. Since the primary audience of these papers are other researchers in the same area, they are presumably able to read past the cruft efficiently.
I also agree that academia incentivizes overselling results. In this case, however, this is a nice result and not oversold by the authors (being somewhat knowledgeable in this field).
They were never what most people thought they were. At their best, they amounted to "a few relevant experts in the same field read the paper and didn't find any blatantly obvious methodological errors."