I remember Jack Dorsey mentioning a feature they thought about but left aside at the very beginning of Twitter: worshipping.
The basic idea was that by worshipping someone you could see every single tweet the person made.
I don't think seeing all tweets helps much but what could be valuable is to see who the person I am worshipping is talking/replying to.
Let's say I decide to worship @Jack.
Every single time @Jack replies to someone, I am notified. The person he talked to could also be added to a specific list.
From there, I'll be able to easily review the profiles of the people he responded to and follow them in a click/tap.
Replies imply a selective process.
People with a lot of followers simply can't reply to everybody who mention them and perform some kind of selection.
This selection process - the work provided by the person who is worshipped - is valuable and can be leveraged in the form of following suggestions for the worshipper.
Simply put, discovery isn't as good as it could be because it's hard to see who people I consider important are talking to.
You can see the important people to follow, but it's not easy to see who they're communicating with on the platform, and that is a richness Twitter could leverage more.
It's a pretty high level feature but I think it could definitely improve the discovery process in Twitter. I would use it.