All this idea is going on assumptions, all of the supporters are assuming the mappers will let players play their colours, while others can be assuming all mappers are going to choose to keep their colours.
All in all this is only a way to justify "Im too lazy to check if colours blend with the background" which is probably one of the most easy checks in a map.
This is just going against the reasoning behind the modding phase of beatmaps, as i said problems like these should be addressed during the modding phase of the beatmap.
And before you bring colour blind people into the equation, take in mind that even colour blind people can distinguish dark from light, so as long as colours contrast there shouldnt be a problem at all.
All in all this is only a way to justify "Im too lazy to check if colours blend with the background" which is probably one of the most easy checks in a map.
This is just going against the reasoning behind the modding phase of beatmaps, as i said problems like these should be addressed during the modding phase of the beatmap.
And before you bring colour blind people into the equation, take in mind that even colour blind people can distinguish dark from light, so as long as colours contrast there shouldnt be a problem at all.