Plus, imagine if you get a sponsorship and end up hating the product (after extended field testing, i.e. actual on-trail usage) but cannot give it a harsh review because of . . . your relationship . . . with . . . . wait for it . . . . your sponsor.
Several online websites are gear review websites whereby a company sends that person gear to test. (Btw, this is another peeve of mine and not directly related to sponsorship.) Why? Because that person uses it for 4 or 5 days and then writes the review!!! Insane. It takes a good year of hard use to really test a piece of gear.