Please note that according to this study people who weren't critically ill still had cognitive deficits.
Otherwise: Yes, other illnesses can have similar effects. Now we have another illness that piles more people on top of that. It adds to the number of people who get critically ill. It's not that Covid is worse than some other health problems, it's that Covid's impact is in addition to the ones that existed.
That sounds like an extreme interpretation that would put the issue forward as a straw-man to be knocked down. Instead, I would just say that COVID is a virus that causes cognitive deficits even in people with little/no other symptoms.
From what I've read (mostly from articles linked here on HN), the problem with COVID-19 is that it is highly inflammatory (in the medical sense, not just the conversational one!).
The brain really doesn't do well with inflammation.
Otherwise: Yes, other illnesses can have similar effects. Now we have another illness that piles more people on top of that. It adds to the number of people who get critically ill. It's not that Covid is worse than some other health problems, it's that Covid's impact is in addition to the ones that existed.