alt Hacker NewsThe article actually maps out the history pretty well. This is basically a recrudescence of the Gall-Peters debate from the 70s, triggered by Boston Public Schools adopting Gall-Peters in 2017. The current wave has taken up the old fight with a less-ugly equiareal map.
...which seems to have been an entirely US-centric debate (especially when it was brought up again in the late 2010s), which explains why Europeans seem kinda baffled by the discussion. But projections that preserve size much better than Mercator were common in education systems outside the US long before the 1970s - mostly a projection closer to Robinson which is a compromise between preserving relative size without distorting shape too much, while still mapped on a common (but not rectangular) 2D area.