A lot of mistakes were made about halfway through the 360 era. They had a rather diverse portfolio back then, and some second parties. They could've done more to secure IP or studios but instead cut ties with nearly everything except for their pillars Halo, Gears and Forza. Worse, they doubled down on Kinect. This cost them as eventually they tried to focus on gaming again but they lost a ton of share by then and they basically never recovered. In hindsight I think MS should've sticked to their guns way back. The Xbox brand was in a good place.
Also, it isn't really on the nose but next to some obvious games such as Wukong, quite a bit of other games skip Xbox such as the Capcom collections, shmups and GG Strive wasn't available until after 2 years. This is a hardcore userbase thats willing to spend. 360 was actually the place to be on this front for a while.
I quite agree other than skipping Xbox, we know the reasons behind Capcom and Wukong, but to Xbox's credit, they've got Atlus on the Xbox the Yakuza series on the Xbox they've made some good moves on the 3rd party front. It is better in some ways than it was or people give credit for.
Kintect really started a rot and it was so sad to see all that money spent on it, instead of going on main stream games . In so many ways Xbox very own 32X moment and just like people at SEGA America, no one at Xbox could see what a disaster it was even when the demos at E3 weren't working and the audience was silent , Xbox pushed on with the crap just like SEGA America with the 32X.
I still think Xbox will have a nice Christmas mind with decent sales and Gamepass will do good with COD and Indy. Its just sad when I look back on how hard Xbox moved to have the likes of SEGA, Fromsoftware , Team Ninja make exclusives for Xbox only to dump them, for Kinect