Despite the lack of history that may or may not support the connection of the druids with the ogham it is still a taught practice of modern druid's even today. Now from my studies and strictly speaking from what I have read the futhark as well as the ogham were never used as anything beyond a divination and writing tool by early cultures. Their magical use is a fairly new concept but it's logic is sound. Symbols hold meaning, idea, and thought. All the things that are a part of magick. Therefor they can hold magical energy. Runes, Ogham, any script that you come across can do the same thing. So they can be used for that. Divination if you want to get technical is done by feeling the energy attuned to the symbol, stone, card whatever. That is why when you first begin to use systems of divination they say it is a good idea to use your own tools because they become attuned to you and your energy. All these of course are my opinion and not proven fact. Decide on your own as with all things.