I wasn't on CK3 when the decision was originally made, but
AFAIK it just wasn't thought to be that important to too many people. I'm unsure how good the reasoning was there: equal chance that it was just downprioritised because it was thought to be lesser used, or that we actually had a look at CK2's telemetry and saw that it genuinely wasn't oft touched.

Now, in these enlightened days of the campaign for customisable feed notifications being the single most organised consumer advocacy campaign in the greater CK3 sphere, that's pretty clear shown to be false either way, so it's something of a moot point. Atm, it's on our radar, it's something we'd
like to have, but it's not free to add. It got pushed out of the limelight for EP2 repeatedly because there was a
lot of UX and Design work in Tours & Tournaments, so there just wasn't ever a time where it was practical to consider it.
We've talked about it since (and towards the end of the last DLC, as things were wrapping up), and, at last check, I believe it's currently in a large bucket labelled "Stuff Wot We Can Steal From V3".