

I might be misunderstanding but that sounds different to a specific alpha channel. Sometimes in game art you’ll store extra information in the alpha channel of a texture. Or even pack four different grayscale images into the rgba channels of a single texture. Is it easy to do stuff like that?
The comments are funny but if you read the article he just did it for the bit. Apparently he changed quite a bit over that time and regretted being an angry forum nerd, so he thought it would be funny to do one last post and abandon the account.