> provide better options for tailoring “the algorithm,”

Instead of a non-obvious "algorithm" with tailoring, just have a social app with a purpose (or per group purpose), and nothing but absolute direct control.

I.e. follow/link with friends, family or whatever in groups. The feed is time-weighted to recent posts or communications. Any other filtering or prioritization can be done, by selection. I.e. deprioritize reposts by default, except persons A, B and C. Etc.

There could be like/dislikes that accumulate into priorities, for those who think that is convenient, but those priorities are just private settings that can be observed and changed.

No hidden/obscure/unclear algorithms, no third parties, no ads, and no Zuck's with any ability to access/impact/insert into the feed.

A scrapbook group, that is just a scrapbook group. Etc.

When did software products/services start "needing" boogymen?

The right platform will allow users to choose between any of the algorithms you described and more.