A racial and gender profiling tool. For example a block/allow mechanism that allows people to self-segregate out by checking off labels from a list, to control what they see and who sees what they share, based on race (implemented by machine learning classification of names/profile images/location). If you want to hide the pin in a pin-cushion, by all means allow filtering on other variables like profession, education, religion etc., but race and gender are the interesting variables, since they account for 80% of all identity politics.

I wouldn't use it systematically myself (only episodically as a filter tool for specific searches driven by ethnographic curiosity), but I see no harm, and a lot of value, in accommodating online what geography accommodates naturally offline. Self-segregation based on homophily is not the same thing as exclusionary racism or systematic institutional bias. It would be sort of an enlightened experiment in post-racial social design. Take the pioneering work of OkCupid in post-racial thinking a step further Quora! Such a daring move would do more for moving the race conversation forward than the anguished holier-than-thou posturing that is the current lame excuse for a real conversation on race.

I think diversity works better if people aren't dragged into it, but are instead allowed control over how much and how quickly they embrace it, with"not at all" and "never" being acceptable positions. A true right to free association. I am no lawyer, but I suspect a feature like this would be more in the spirit of the US constitution than enforced diversity.

Multiculturalism should be a choice whenever it concerns individuals in their individual capacity using resources that don't force sharing. If diversity is truly valuable, self-segregating people will naturally open up over time, and advocates of diversity will have empirical proof to back up their claims instead of vaguely pious assertions. And presumably, voluntary embrace of diversity is more valuable than "tolerance" enforced by being forced to share scarce resources like land, which is irrelevant online. Given that body language and other cues are missing online, it would actually be nice to know that people of different races you interact with have actually opted into those interactions.

Conversely, maybe those who assume that self-segregation is "bad" without any proof will end up surprised by the kinds of value it creates. Liberals probably think this is a "give racists enough rope to hang themselves" experiment. Conservatives probably think it is a good "enough with political correctness" idea. If both sides think the idea will serve their ends, it sounds like a genuine scientific experiment hypothesis to me. Let's A/B test "racism"!