How would you notice? It's pretty hard to prove something exists if you don't know about it (ie. every political scandal ever).
They claim every post should appear in your main feed in sequential order, but I really don't trust it anymore. Human error included, sometimes I scroll right past the posts from authors I am looking for and don't realize it. By the next day or two, it's already buried and gone.
There seems to be a lot of concern over people leaving steem, but I think a lot of it is because authors are feeling there is a lack of exposure to their posts, and rightly so if curators cannot find them.
Glad the search tools people are sharing are helping caring curators like you @mattlovell. Be sure to review your favorite people you follow to make sure something weird hasn't happened, like recent activity you did not notice, or you following/mute settings are different than you expected.