The other issue is that even if you had an office application with feature parity to Powerpoint, Powerpoint is still the one that everyone else is using. As a result, perfect file compatibility is more important than features. I haven't used Open/LIbreOffice in about two years - I stopped because I could not collaborate with colleagues on the same PPT file if I was using LibreOffice. Little things in format and layout would get messed up when you went back and forth.