Coordination and negation

Subordination structures facilitate VP ellipsis, strict readings anyway – but stripping and gapping require coordination structures or (comparatives or) separate turns in dialogue.

Johnson (2019) (Gapping and stripping) outlines two ways to account for that, in terms of the 'small conjuncts account' (section 23.4.1) and in terms of antecedence conditions (section 23.5). Which way do you find more appealing, or more convincing?

Coordination structures, it is usually assumed, can be formed with and and or but also with but. Are stripping and gapping cases with but and negation in the left or the right conjunct problematic, empirically or theoretically, in relation to 'small conjuncts' or to antecedence conditions in terms of discourse relations? One example:

(1)  If you eat fish but not meat you are a pescatarian.