BGP and aggregation

In the referenced message, E.B. Dreger said:

* BGP is an EGP, not an IGP

BGP is one half of an IGP, it is the "where to go" half.
You generally run another IGP along with it to provide the
"how to get there" half. Most folks run isis or ospf to
transport router loopbacks and other next-hop information, but
still transport the majority of routes via bgp.