"Reverse chron IS an algorithm."

Yes, but even more than that, we're all of us making our own custom algorithms by the way we arrange our accounts. The software and services we use provide us with particular tools for doing so. Reverse chron and follow are the basic underlying tools, but there's also block account, block domain, mute account, mute word, follow hashtag, mute replies from this account, and so on. Even choosing a host instance can be a means of shaping your algorithm.