It's not 'pixel peeping'. Dynamic range, low light performance, and bit-depth for portraiture are evaluated by DXO and I trust their rating system. In purchasing a camera, I want the most "bang for the buck". 1. Sensor performance. 2. Lens selection (why I'm not in the Sony camp -- and spare me your talk of clunky, kluge, and expensive adapters) 3. Ergonomics (call a DSLR "clunky" if you will. However that nice deep grip on the right side of the Nikons and Canons is meaningful -- strike that "mandatory", especially with larger and heavier lenses. Additionally, the "mirror hump" might ruin the camera's looks, but that saves me valuable battery life and I'm seeing exactly what's in the scene not an electronic representation. I prefer this -- especially for the battery life dividend. The RF form factor may "look" cooler but I want my grip and I want a 900 shot fully-charged battery life). 4. Cost -- bang for the buck.
I don't want to bash Leica. But they charge a premium for their cameras -- and not by a little, and they fall behind in the most meaningful sensor metrics related to digital camera performance and not by a little. My used D600 from 2012 rates a 95 on DXO. It cost $650 (again, to be fair, that's a used price but you ain't getting no working and in great condition digital "M" for that). The full frame Leica M10, which costs nearly $7000 new, rates an 86 and it's 5 years newer than Nikon's entry-level FF. By comparison the little D5300 that I paid $300 used rates an 83 with a cropped sensor. Performance-wise, the new full frame M10 is closer to an old entry-level Nikon aps-c camera that cost a fraction of the M10. And the latest M has nowhere near the sensor performance of a 5 year entry-level FF Nikon model released in 2012.
But as long as people keep buying them at their asking price, Leica has no incentive to put better sensors in their digital cameras I guess. That said, for a film camera where you're pairing it with one of their superlative diminutive jewels of a 50 or 35mm lens, the RF form factor works, and Leica still reigns supreme. Digital? Wow. C'mon Leica. You should be the class leader here and the simple fact is, you're not. Not by a long shot in terms of the metrics that matter most. And Leica's digital price/performance can only be described as abysmal.