This is absolutely not self evident.  It is a narrative that is repeated over and over, but it is entirely wrong, as I explained already many, many times.  

The number of different, identical copies of a cryptographically signed document that are stored world-wide, from the moment there are several (say, a few 10 or so) doesn't increase its cryptographic certainty.  

Suppose that 10 people are each in possession of a cryptographic secret key of which we all know the public key, and suppose that these 10 people sign documents.  We can all verify the signatures of these documents.  How many independent copies do there have to be in the world on public repositories, in order for you to feel secure that you are able to access some of them when you want and are able to verify their authenticity ?   Do we need thousands of repositories ?  Is it useful that Joe and Jack put up a server in their basement with those documents ?  Or can we live with a few tens of independent servers (for instance, of these people themselves) ?

It is clear that the cryptographic verification of these documents is independent of the number of independent servers there are in the world.  If my neighbour Joe cannot afford to set up a home server of these documents, that's not going to stop me from being able to verify their authenticity if I download them from one or other big data center, right ?

Now, we have essentially 10 big mining pools that are the sole authors of the bitcoin block chain.  How many copies of that chain do we need to serve, all over the world, in order for me to be able to verify the authenticity (that a piece of it I download, is of the real block chain out there made by these 10 mining pools) ?  I would think that a few tens of copies that are publicly available are good enough.  That my neighbour cannot have a server in his basement, is, just like before, no problem.

I can easily check, from the moment that I have access to any public repository of the entire block chain, that the small piece I need, is authentic, that is, belongs to the sole and unique chain that is out there, made by these 10 mining pools, like I could verify that the document I downloaded was cryptographically signed by one of the 10 authors of these documents.

And when there needs to be a few tens, or a few hundreds, of public repositories of blockchain in the world, then there is no "data burden".  Your average datacentre handles WAY WAY more data than the bitcoin block chain, even in your wildest dreams.  Compared to an IPTV data center with VOD, the bitcoin block chain, even with VISA-like transaction rates, is extremely small.  That's what Satoshi already told us in November 2008.  It was obviously right.

And nothing is gained by having thousands and thousands of identical copies ; if, in order to have those thousands and thousands of identical copies everywhere, we cripple the system, we're totally out of our minds.  That is similar to not wanting to broadcast TV shows over the internet at more than a 250x125 pixel resolution, because if every poor dude in the world has to keep all the TV shows on his basement server, we have to limit internet TV.  

I will ask something else if you want to put that in doubt: how many independent repositories are there, publicly available, of the bitcoin core software ?  There is essentially only one, as far as I know, that is on github.  I don't know of other servers of the git repository that are public.  At best there are the Torrent seeders, but that is not a genuine git repository.  How many are there ?  So if only a few software repositories are available, why should there be thousands of block chain repositories ?
The single github repository is enough, as long as it is working, because we have the cryptographic signatures of the few authors (think of my 10 people on the top of this post).  If github breaks down, I'm sure that each of these authors can set up another repository somewhere else, and by verifying their signatures, we know it is authentic.   Replace "github bitcoin repository" by "block chain repository", and replace "signing author of Core" by "mining pool", and "signature" by "proof of work", and you see the analogy.