Years ago now, I used to be a YouTube mod for a large British gaming publication. (It didn't end well, but that's a long story for another time.) Anyway, I saw them cycle through different presenters for their YouTube channel. I saw them set up a new publication for tabletop gaming, also with YouTube content, and hiring people to present on that channel too.
At least on a superficial level, these folks were all presenting as well meaning white people who favour diversity. But in practice, everyone on the YouTube channels was white, and the diversity was basically queer white women or guys. Even when they had the opportunity to set up a whole new publication on tabletop gaming, with a whole new YouTube channel for it, it was only after some time that they finally hired a single black presenter.
These were the well meaning white folks. Yet somehow homogeneity prevailed for years and years. And I can tell you that I knew people of colour who applied for those roles when they were advertised. It's not as if there was a shortage.
Basically, I think "tech" as a background in the current site discourse about why Cohost is so white, is a factor because many tech-related industries still skew white. Many other industries too, but we're on a social media platform in particular, which is an environment that depends on tech. Whiteness is still what most people know of the culture of these industries. If I say "tech bro", I think most people imagine a white tech bro. "Queer" is also a factor, because it's still easier for white people to surround themselves with other queer white people, and feel they are "being diverse enough".
For straight, cis white people, for instance, having a white gay friend/colleague or a white trans friend/colleague who manages to pass, can be an invisible difference that they can put out of their minds for much of the time. (Remember when the standard in the US miltary was "Don't ask, don't tell"? Out of sight, out of mind.) But being a minoritised person of colour can mean visual differences that are harder to ignore, or that provoke more anxiety about accidentally being seen to be being racist.
I remember the time I was the trainee representative on the board of the psychotherapy training institute I did my training in. The secretary at the time was another Chinese woman. There were like, 3 ethnically Chinese people doing psychotherapy training in that modality at the time, and we all knew each other (it was a small modality.) 😂 And 2 of us were on the board. And the white person who was in the role of Chair kept mixing me and the secretary up. She didn't do it to anyone else on the board (the others were white folks, some of whom also happened to be queer - so functionally a more diverse group than much of games journalism. 
) She just kept referring to both of us with each other's names.
You can bet at one point we said something to her, because it was clearly an issue she was having with us in particular. And I would have said she was genuinely well meaning. Not someone that was in any way setting out to be racist. But somehow she struggled with unconsciously confusing us with each other. If the Board had been entirely white at the time, she wouldn't have had a problem. I am 100% sure she wouldn't have wanted the Board to be entirely white, but I am also 100% sure that having POC on the board saw her feeling more personal and professional discomfort, because she had to grapple with the parts of her that were struggling to see us as distinct individuals. She had to confront something discriminatory in herself that she wouldn't have had to deal with if it was a more homogenous group.
So what I'm saying is that it's not enough to be well meaning. In terms of homogenous hiring, some ways of thinking can perpetuate homogeneity even if on a surface level, people want to think of themselves as supporting diversity. For example: "The new hire should be a good fit with our team culture." But if your team is all white, then the easiest fit will often be other white people. Or "the candidate should be able to conduct themself professionally". But norms that people consider to be "professional" are also culturally determined. (And making "professionalism" a bar to entry can also be a class-related deterrence - games journalism still tends to be white and middle or upper middle class.) You get the idea.
Another thing I've frequently seen is predominantly white orgs offering entry level "mentoring" roles to people of colour. At which point the person of colour enters at a junior level, and is "mentored" to accept the existing culture, and has very little chance of questioning or changing the status quo in the process. Look how often "mentoring" is offered to people of colour as an answer to a lack of diversity, as opposed to how rarely positions of power are straight up offered to people of colour who are already experienced in their field. I've seen gaming publications offer mentoring for POC, much more than I've seen gaming publications hiring editors or senior editors of colour, for instance.
What I'm saying is that it's very easy for any place to stay predominantly white. And even places that consider themselves as being for leftists, or progressive, or caring about diversity, or whatever. It's a lot easier to make some partial, surface-level gestures towards "diversity", and to stop at that, than to ask: How have we made an industry, a culture, a social space that historically excludes people who aren't like us? Or: What discomfort are we avoiding when we historically exclude people who aren't as similar to us?
Anyway, that's enough dipping into the discourse for me right now. I'm finally starting to emerge from a long stretch of being depleted by stress and anxiety, and I don't want to spend all of my Friday evening on this. I'd rather relax and go play video games for a while. 
