Ligatures not working (Keynote)

According to Keynote Help, ligatures can be enabled for selected text or a text box by following certain steps, see https://help.apple.com/keynote/mac/9.0/#/tand7ac3366f

There are several problems with this:

1. It has no effect when I try it.
2. Even if it worked, it's ridiculous to have to insert ligatures manually. When you type "find" or "fluffy" in a presentation, the ligatures should just appear (as they seem to in this post!).
3. When you insert ligatures manually, your text is marked as being misspelled.

I tried it with Keynote, fonts Didot and Palatino. I also tried it in Pages, same behaviour. (Font: Baskerville regular, and it has ligatures.) Why should ligatures work better on forum posts than in a formal presentation?