https://www.youtube.com/watch?v=WsUax48eBSY
A very good discussion by Digital Foundry.
The TLDR is the internal architecture as well as lack of CPU and GPU power is very dated. The PS4 Slim, XB1X and PS4P all have similar architecture so are easier to develop for. Most developers don't want to develop for the XB1S because of all of this. Being forced to release their games at 30fps and other issues that other consoles don't have.
The Switch at times is below the XB1S quality and at times the Switch games are on par or even slightly better. The main catch there is the Switch is a tablet console. People are ok with the sacrifices for portability and still many Switch games do look relatively good too. Playing games like new DOOM on the go, sure it's not 1080p at 60fps but you can play it anywhere and that's the draw. A sub par experience on a TV only console though? That's kind of unacceptable these days. That's what the XB1S is delivering.
The XB1S (and the OG too) internally is just a better 360. Sure the 360 back in the day was cutting edge byt today tech has moved on. As evidenced with the PS4, PS4P and XB1X all moving to a different internal architecture.
Personally I can see Microsoft soon-ish announcing the XBox 2 and maybe having some of the games have backwards support with the XB1X only. Honestly apart from being used as a streaming box, the XB1S is a dead console in my opinion. A PS4S is very cheap these days, plays all the multiplats and PS4 exclusives all very well on a 1080p television. Also there's not that many XB1 exclusives anyway worth getting.
What's your opinion on all of this?