I think you're misunderstanding what we mean by NASApunk; eezo will exist in human society, but it will be significantly curtailed in its use. Scout ships and colony ships are the only things that need it to travel through the Relays, but defense fleet and civilian infrastructure can all be done without eezo (the ships just won't have shields and can't go through Relays). NASApunk isn't "humanity invents a brand new tech tree that trivializes eezo", it's "humanity learns how to transport things from Relay to Relay with their limited supply of Relay-capable ships."