A border router that is not able to serve blocks is still protecting consensus rules, that SPVs do not.
If the network would only consist of SPV nodes only then e.g. a majority coalition of miner could increase their reward at will.

Archives need a different solution.

Regards,

Tamas Blummer
http://bitsofproof.com

On 09.04.2014, at 17:47, Mark Friedenbach <mark@monetize.io> wrote:

> On 04/09/2014 09:09 AM, Tamas Blummer wrote:
>> Yes, SPV is a sufficient API to a trusted node to build sophisticated
>> features not offered by the core.
>> SPV clients of the border router will build their own archive and
>> indices based on their interest of the chain therefore the
>> border router core does not need to store (and process) anything not
>> needed for consensus, its memory
>> or disk footprint would be as low as an optimal storage of UTXO.
> 
> Storing zero full blocks does nothing to aid the network.