Emoji were in color before they were added to Unicode. Even the original iPhone 3G Emoji release pre-dated their addition to Unicode (Apple used the SoftBank encoding). They were even in color on flip phones as far back as 1999 https://emojipedia.org/softbank/1999/
Seems a decent solution to me. Monochrome screens can just ignore the colour character.
As well as adding colour browsers display emoji at a larger point size. It is really annoying when some pre-emoji symbol (like the phases of the moon in TFA) gets emojified and where your document had some discreet use of symbols it now has huge colourful icons drawing the eye.
And afaict there is no way of turning off this behaviour globally.
Edit: apparently HN limits the number of emoji per post, I originally included several.
Redundancy has never been a problem with Unicode. After the decision was made to add the symbols of the original encoding to the list of Unicode characters, they had to add all heart variation, otherwise it wouldn't have been able to be backward compatible.
Or alternatively add a color modifier? I'm not sure that would have been a better solution.
I am surpeised HN allows any emoji an all. Pretty sure they have been totally banned in the past. It seems like the orange heart is now (or has always been) whitelisted. 🧡🧡🧡