At least a few active DP → HDMI 2.0 are okay at 4kp60. For example, these[1][2] do 4:4:4/RGB 4kp60 fine, though they're limited by HDMI 2.0 to 8 bits per color channel at 4kp60 (higher bit depths work fine at lower resolutions and frequencies, or with chroma subsampling).
In my testing (several years ago), at least half a dozen other similarly-priced DP → HDMI 2.0 adapters purchased from Amazon were limited to chroma subsampled output (4:2:2 or 4:2:0) at 4kp60, which is obviously unacceptable for desktop use, so I do see your point.
I've used the linked adapters successfully now for several years with both a 2013 Mac Pro and a pair of DP-only AMD GPUs (WX 3200 and WX 4100), all connected to a 2019 LG TV, and, while testing, confirmed all claimed signal outputs using an HDFury Vertex.
In my testing (several years ago), at least half a dozen other similarly-priced DP → HDMI 2.0 adapters purchased from Amazon were limited to chroma subsampled output (4:2:2 or 4:2:0) at 4kp60, which is obviously unacceptable for desktop use, so I do see your point.
I've used the linked adapters successfully now for several years with both a 2013 Mac Pro and a pair of DP-only AMD GPUs (WX 3200 and WX 4100), all connected to a 2019 LG TV, and, while testing, confirmed all claimed signal outputs using an HDFury Vertex.
[1] https://www.amazon.com/dp/B00S0BWR2K
[2] https://www.amazon.com/dp/B00S0C7QO8