True that @post. In fact, I tried the same as sRGB is "standard RGB". but that check mark didn't do anything different. Still, the RGB standard is three sets of 2-byte numbers in base-16 hexadecimal so 255 x 255 x 255 is like a 16 million+ count pile of colors. I can't imagine picking a color that's not covered in that color set lol. So, I'm not surprised the sRGB made no difference in this case.
However, once I saw it, I figured the embedded color management "stuff" like iCCP, or whatever, etc has an effect. I don't know (or care) what these color management inserts do, but at least I can turn them on and off.