Maybe the same reason why Google keeps Firefox alive - to be able to show there is no monopoly in some category of software.
This already happened, some sites wouldn't work in Firefox unless Firefox had the Chrome user agent string.
Also who is going to sue them? Firefox? That's like kicking yourself in the balls.
But Adobe recently acquired Allegorithmic and their 3D texture tool Substance.
https://techcrunch.com/2019/01/23/adobe-acquires-allegorithm...