We didn't have to toss out everything we learned about viruses and start from first principles, but certainly people's irritation with COVID restrictions seems to have provoked people to ignore decades of research to the contrary to make bizarre assertions like you can't catch viruses outside or get reinfected (ironically the early scientific and mainstream speculation about if COVID would be different was mostly taking the optimistic tack that COVID might be less likely to cause reinfection than respiratory viruses endemic in the human population like flu...)
Same goes for the T-cell immunity really: it was pretty much a given that the body's normal immune processes still applied to coronavirus, but what was novel was the unscientific community insisting that they couldn't possibly be reinfected and a course of vaccines couldn't possibly give them any benefit to their immune system after they'd been infected (someone should tell all the old people who get flu shots every year!)
> someone should tell all the old people who get flu shots every year
What we call the flu is not a single virus that comes once a year. It's different types of virusses each time, and the flu vaccine targets the most likely candidates of that year. So no, you don't generally get REinfected with the flu, because it's a different virus. Some of the virusses that we consider 'the flu' are actually corona virusses, and perhaps covid19 will join that list as it becomes endemic.
No one who is familiar with viruses considers other human coronaviruses to be "the flu". They aren't even in the same phylum! All influenza viruses are Negarnaviricota whereas all coronaviruses including SARS-CoV-2 are Pisuviricota.
There are four other endemic human coronaviruses which typically cause common cold symptoms. Those symptoms are clinically distinct from the flu in most cases.
What we call the flu also includes a wide variety of viral illnesses better known as the common cold, which includes some coronaviruses - the flu shots offer no protection against most of these different viruses
What medical practitioners call the flu is a small subset of influenza viruses common in humans, each with a high potential for reinfection, including reinfections within a year (as well as constantly evolving variant strains, just like COVID)
Same goes for the T-cell immunity really: it was pretty much a given that the body's normal immune processes still applied to coronavirus, but what was novel was the unscientific community insisting that they couldn't possibly be reinfected and a course of vaccines couldn't possibly give them any benefit to their immune system after they'd been infected (someone should tell all the old people who get flu shots every year!)