Why do you need a theory to explain the skin tones? Why does it matter at all? What is so triggering for you about a web page without a depiction of a white person?
I'm not sure if it does, but the topic was being discussed so I joined in.
>What is so triggering for you about a web page without a depiction of a white person?
I'm not sure if "triggering" is the right word to use, but although I used to think that representation didn't matter (a la skin tone variants in emojis) I now realize that it's a nice gesture to be included in art asset packs and marketing material. Next time someone talks about how they added twelve different versions of a thumbs up asset I'll roll my eyes a little less hard. ;)