Wrong. Freezing temperatures are by far the most challenging environments for plants to deal with and only a limited set of species are well adapted for cold climates. Meanwhile warm climates mean year round growing seasons and the widest range of species that thrive, this is why you can grow almost anything in tropical zones and get much more productivity out of that growth.

See: https://www.gilmour.com/planting-zones-hardiness-map

If that were generally true then tropical zones would be overridden with bark eating beetles. Vastly more biodiversity occurs in tropical zones than in Arctic and Temperate zones.