Programmer Humor

Some people actively desire this kind of algorithm because they find it easier to find content they like this way.

Raw chronological order tends to overweight the frequent posters. If you follow someone who posts 10 times a day, and 99 people who post once a week, your feed will be dominated by 1% of the users representing 40% of the posts you see.

One simple algorithm that is almost always better for user experiences is to retrieve the most recent X posts from each of the followed accounts and then sort that by chronological order. Once you're doing that, though, you're probably thinking about ways to optimize the experience in other ways. What should the value of X be? Do you want to hide posts the user has already seen, unless there's been a lot of comment/followup activity? Do you want to prioritize posts in which the user was specifically tagged in a comment? Or the post itself? If so, how much?

It's a non-trivial problem that would require thoughtful design, even for a zero advertising, zero profit motive service.