Influenza can be a very serious illness... everything about Covid sounds like one of the major flu epidemics (like the Spanish Flu as featured in Downton Abbey).
Surely the issue is that we've downgraded the common meaning of "flu" to "nasty cold that you can't battle through a day at work with" and forgotten that it's one of the biggest killers in history.
I'd say that Covid-19 being very much like Influenza (symptoms, infectiousness) is actually true, but calling it "just flu" understates the potential seriousness of both!
Sorry for the rant - been pissing me off since February!