Earlier quoted context omitted.
I had the opposite experience. If something's easy to remember, I don't need Anki. If something's hard to remember (I really struggle with birthdays, for example), even Anki doesn't help! The cards all end up as "leech" and Anki stops showing them to me. (I found this behaviour amusing, since the whole point of using Anki is to help me learn things that are difficult to remember!) They say if a card is ending up as a…
Why would you need to learn birthdays (except maybe closest family)? It's maybe the canonical thing to put into a calendar. "Because I want to" is obviously fine, but it still reminds me of the infamous "capitals of the world" flashcards that spaced repetition practitioners warn against.
I have a "Roman Emperors" Anki deck. It serves absolutely no purpose except making me feel good about it, but it works well (except maybe for the final few emperors, those tend to be leeches).