Maybe a lot of the people coming here actually do want chronological feeds. I know that's what I actually prefer. A smaller follow list in chronological order. Both could be catered to of course. Or a chronological feed of a smaller list of people. But you're right. However even when clients do implement them, they likely won't be the default. And for it to catch on, a big client needs to default to this algo. The chronological sub feed for YouTube exists and is better for seeing the actual content you're subbed to. It works better for most people than YouTube's home page. But the default home page is how 90% of people use YouTube.