This type of manipulation and plagiarism may be partially to blame, but the academic writing style has also gone completely off the rails to the point that half the journal articles being published today read as if written by some kind of paper writing AI robot even when I am quite certain that that isn't the case. And no, I am not talking about cases where the author is writing in a non-native language.
I have a theory that it may have to do with imposter syndrome and a need to sound smart. The author, fearing that they don't really belong and at any moment will be found out, therefore never making tenure, starts jamming academic sounding words where they don't belong and stretching sentences with commas and semi colons until the whole thing is just as insufferable to read as it was to write.
There is also the possibility that there are just a lot of terrible writers out there.