Yes most people say the colours no matter what it's display don't look naturally - more artificially enhanced but if you look at the same thing with the human eye you noticed world's of difference. As far as I know samsung's oled panels are locked as far as saturation goes, as I don't believe you can even adjust it in any way to even come close to say lcd - it's basically all or nothing. It may be an inherent feature of the technology where you cannot tweak it. As my previous post indicated, anything with a white background on oled will drain power pretty quickly. The major advantage of oled is no backlight so the display can be thinner.
You did qualify your statement with "As far as I know..." and that was a smart move. Simply put, you're wrong. Not you, but multiple people in this thread are quoting old OLED info as if it's still relevant today. Samsung phones come with 4 distinctly different display modes for color. Used to be 5, but Dynamic was incorporated into Adaptive.
-Adaptive mode (default) - oversaturated by up to 133% (The 133% oversaturation used to be Dynamic.) This is the mode everyone comments on in these threads. Adaptive mode changes the colors based on factors like content, ambient lighting, etc.
-AMOLED Photo - uses Adobe RGB Color Gamut instead of Standard sRBG/Rec. 709 Color Gamut.
-AMOLED Cinema - enhances colors to match theater type of experience. Severely oversaturated colors. Almost cartoonish imo, but weirdly enough I have a buddy with red/green color blindness who swears by this mode.
-Basic mode - uses Standard sRBG. Most accurate colors; 101% to Standard sRBG. That's the highest color accuracy rating on a smartphone.
The Samsung screen was judged to be the best overall screen on any smartphone (iPhone judged to be the best LCD screen). "So… The Galaxy S6 matches the Galaxy Note 4 in overall display excellence and record performance and joins it as the Best Performing Smartphone Display that we have ever tested." - Displaymate
The battery drain on primarily white backgrounds has also been improved by 20% over the S5 even though it's pushing 2x the pixels. Both Lollipop and Marshmallow are primarily white and the phones run fine on them.
With Apple's control of hardware and software, and the improvements in OLED technology, there's no telling what they could do with this tech by 2018.