explain extension/proof computation benefits to column partitioning

Author: ralexstokes

EIPS/eip-7594.md

@@ -88,6 +88,8 @@ PeerDAS defines a sample as a "column" which is a cross-section across _all_ blo
 The sampling scheme could be defined over rows but then any reconstruction strategy would need to work over "extension" blobs that do not a priori exist on the network.
 Reconstruction becomes much more tractable by working over columns as nodes can be assumed to have much more of the complete data by default (e.g. because most/all of the blobs are in the public mempool).
 
+Another benefit is that sampling over rows requires _column_ extensions which would have to be done at the time of block construction, i.e. on the "critical path". Sampling over columns requires row extensions which can be done in advance (not on the critical path), and moreover proof computation can be outsourced to senders of blob transactions.
+
 ## Backwards Compatibility
 
 This EIP is fully backwards compatible with [EIP-4844](./eip-4844.md).