[acdha]

Don't blame Microsoft – they're no stranger to the game but this has been exploited since the Supreme Court created software patents as a category. Here's a reaction to flagrant trolling back in 1993:

https://www.fourmilab.ch/autofile/www/chapter2_105.html

Prior to that, you had companies like IBM, who were famous for using their hardware patent library as a club to get competitors to sign licensing agreements.