WebDriver - why not to use a singlton for it?

IS there any reason not to define the driver(let's say i need one per each browser) as a singlton class?what is the best method to use it over different classes(in Java/python for example)?
Maybe there is another better way for it?Like to create an abstract class?
Please let me know what do you think..

I'm creating a singleton in C#, initializing it once and then calling it with (ex) FFDriver.Instance...

I don't know of any reason not to do it like that.

i am not understand your question, can you clear your question.