If you would have done your research more carefully you would have known that the spyware/adware you refer to comes from the "Sponsor". Installing this sponsor is optional. The user is free to not install this sponsor on every installation or upgrade.
Also, the sponsor can very easily be removed should you have installed it by mistake. Read
How to uninstall ad-ware/sponsor for detailed uninstall instructions.
If the sponsor will be installed depends on a very simple question whether the user accepts or refuses the installation of the sponsor:
What the sponsor does is explained in the Sponsor Program License Agreement which users
must accept before the sponsor can be installed.