Concerning the smoothing, I presume this is macOS’s glyph dilation. pcwalton reverse engineered it in order to replicate it in Pathfinder (so that it can render text exactly like Core Text does), concluding that the glyph dilation is “min(vec2(0.3px), vec2(0.015125, 0.0121) * S) where S is the font size in px” ( https://twitter.com/pcwalton/status/918991457532354560 ). Fun times. Trouble is, people then get used to m…
I tried turning off smoothing and frankly the text was uncomfortably thin to read. I guess maybe their font should just be bolder by default so you don't need the glyph dilation to compensate.
I have a vague feeling that Macs also have somewhat different gamma treatment from other platforms, which would be likely to contribute to thickness perception.