"Unauthorized" third-party controllers and accessories are to be blocked on XBoxes for "security and safety" reasons.
"Microsoft and other licensed Xbox hardware partners' accessories are designed and manufactured with quality standards for performance, security, and safety. Unauthorized accessories can compromise the gaming experience on Xbox consoles (Xbox One, Xbox Series X/S.) Players may receive a pop-up warning that their accessory is unauthorized. Eventually, the unauthorized accessory will be blocked from use to preserve the console gaming experience. For a full list of accessories that are supported on Xbox consoles, please visit www.xbox.com/accessories, our support pages here and here, and our Designed for Xbox Partner Hardware Program page here."
It could also generate money for Microsoft, marginalize interoperability standards that the world takes for granted, make it impossible to sell DIY or custom hardware that works without infringing copyright law, give Microsoft more control over products sold by other companies, and create a clandestine market for junk that claims to circumvent the locks.
