Same reason as Sony. K&M advantages as well as them being competition and possibilites of security risks and the obligation to keep the service gamers are paying for stable, safe and on an even keel. It's not stupid at all but what is stupid is MS subtley calling sony out for it, a dick move that I hope backfires on them.
As a console owner I buy into a closed system, its one of the many reasons I choose console over PC these days, no hassle, no hackers, no unfair advantages all tied by the same EULA as do many other gamers.
If you want to play on a certain platform then buy that platform.
Honestly, I've only run into a so called hacker twice. Back during my days of playing Fall of Cybertron on the 360, I ran into cheaters far more times than I've run into on my PC, In fact , most games I've played online on PC have had an anti cheat method in place that auto bans them on the spot.
I've many reasons why I chose to move to PC, but cheating wasn't one of them, as there are cheaters to be found on any playing field, any sport in this known world as well.
Also paying for "stable" services is rather crock, especially when those servers and online services experience multiple levels of downtime. With the money the Sony and MS online service has made, they shouldn't go down at all, and if they do it should be for 10 mins tops.