If it weren't for Elon Musk, Dogecoin would have failed long ago.
In this case, it is unclear how Doge existed before, until Elon Musk paid attention to it. Of course, having such a patron as Elon Musk would be good for any project, but this is not a decisive factor in the existence of the coin. So in any case, the Dogecoin community is more important than the patronage of Elon Musk.
Doge existed before, but Elon and his army of followers pushed Doge's price to the sky! As I remember he was accepting Doge for buying Tesla cars, I wonder how many people (if any?) purchased Tesla with Doge coins?
I agree that one person is not so important factor, but if take Doge as an example, we saw what happens when one person with a deep pocket and lots of followers decides to enter the project with full power! I guess this can happen again, to any other coin.