It's making sure that you're not liable for someone's house burning down because they bought the el cheapo bulb from knockoff brand C. This is standard protective legal boilerplate to protect philips in the unlikely event.

Also, want to point out that philips is not "extorting money" from other companies - they can choose to enter the "friends of" program to make the general consumer feel better, or choose not to, at their discretion.

The class of user that realizes any zigbee bulb will work with a hue hub is already technically proficient, and will more often than not be willing to take on any associated "risks."