So that you can run interactive 3D applications like games in your browser.
Hardware info does not need to be sent server side to accomplish this. OpenGL and Vulkan APIs can both say what the current hardware supports without hardware identifiers. A malicious website could probably still fingerprint based off those listed features, but that's just a justification for "don't accept requests for GPU hardware acceleration without user permission". Currently modern web browsers broadcast it no matter what the page is requesting.
To adjust the performance of a web application to save more power.
Name me one web "page" that does this. A web "application" doesn't count. My native browser should should never broadcast this, ever.
To give you matching website.
Can/should be ran client side.
Again to adjust performance or to pause an application.
Can/should be ran client side. Its none of the websites/applications business whether I have frozen its process or not.
Is often used to give you a download link that matches your OS.
A small quality of life, isn't worth it. Thankfully its the easiest thing to fake/lie about on this list. Most of these "features" on this list are not user facing and cannot be turned off with basic configurations.