What happened to the annual flu season?

Data coming in indicates that 2020-2021 flu season has been eliminated. Measures to slow the COVID pandemic appear to have almost completely stopped the spread of flu this year. An April 2021 article in Scientific American, Flu Has Disappeared for More Than a Year, included this data:

Extended data through this month indicates that the flu virus never took off. Infections in North America, temperate South America and Oceania all remained at very low levels so far this year. SciAm commented: "When Scientific American first published influenza data in November 2020, the 2020-2021 flu season looked like a possible no-show. Since then, cases around the world remained near zero."

At least, one can reasonably believe that (1) masks are effective to some extent for flu and probably most other virus diseases, and (2) COVID is more infectious than this year's flu strains. A few science deniers continue to argue that masks don't work and COVID is a hoax. The flu data indicates that masks do work to at least some extent and flu isn't responsible for deaths that have been attributed to COVID.