It's because of obnoxious DRM garbage. I doubt helps these companies since the unlicensed users are starving musicians and kids with no money who aren't going to magically spend more.
As a company. Since they have been bought by an "investment company" they have been in a downward spiral. It will take a few years but the process started.
Go to Plugin Alliance [0] and select any plugin and when you scroll down you'll see that they are Windows and Mac only. Same for Plugin Boutique [1].
[0] https://www.plugin-alliance.com/en/products/amek_eq_250.html
[1] https://www.pluginboutique.com/product/1-Instruments/4-Synth...