There is nothing 'stopping' people per se but at the end of the day why does the average person want or need to use it currently? It doesn't really benefit them in any way at the moment. It could in the future but not right now. People were also probably wondering the same thing about the internet or mobile phones when they first came out. Why aren't more people using them (at the time)? Because things take time but good ideas get adopted eventually they just take time to catch on with the public.