Depends what you mean by "Fast". I guess you could argue;
A) DAB has more bandwidth than FM, so it is capable of getting more information to the user...
B) The frequency is higher, meaning you get more waves per second, ie it's a faster way to get 1 million "waves"...........
But I think this was written by some marketing drone with no idea how it all actually works & probably imagines it's like broadband & speed is actually a major thing for the consumer when listening to what is, effectively, an unbuffered media stream with no reliability built in.
DAB is now pretty good in the parts of the UK I frequent. There are occasional black spots, but I can get to Scala Radio, Jazz FM, Planet Rock and so on just fine for most of the UK. Trouble is. I can get FM basically anywhere.