Not an assumption at all. That's from my subjective past experience, from having conducted qualitative research experiences in this area as I interviewed and taught students. I shared that experience in my original reply and would love for anyone else to do the same, referring us to their past experiences even anecdotally, rather than forecasting woe via subjective intuition.
My real world experience has taught me many developers cannot write (code or prose) and would rather jump in front of a bus than write their own original code. The next time I am tasked with candidate selection I will use an essay assignment as the first round of filtering.