a design without partitions and where every full node verifies every transaction, which obviously can't scale and which due to economics that I
A partitioned network operates exactly like two independent networks. If invalid transactions propagate throughout a network, that network is in trouble, regardless of whether there are partitions or not.
You apparently still haven't comprehended that for a
strict partitioning that obeys the Nash equilibrium, i.e. for transactions that are never allowed to cross-partitions, then the partition doesn't need a separate PoW nor separate block chain. It can be essentially merge-mined (but in the same block chain) without impacting the Nash equilibrium for the block producers. And my other point was that strict partitioning can't exist for scripting yet it can exist for asset transfers (e.g. crypto coin transactions).
#2 is why the design for partitioning (or delegation of validation) has to maintain a Nash equilibrium, meaning the requirement that there exists no game theory advantage for partitions (or delegates) to lie about their validation. This point about Nash equilibrium has been explained to you numerous times!
My point is that if you allow block producers to produce invalid blocks, that will be gamed by those who do validate, leading to SPV miners being pushed out of business.
You apparently still haven't understood the point. The blocks are not invalid when a
strict partition is invalid.
Of course one might argue that strict partitioning (thus by definition is without cross-partition transactions) is not that flexible. But nevertheless the point remains that there is a design which refutes your assumption.