Post-punk and the guitar as a rhythm instrument rather than a melodic one is a fundamental reorientation that shapes everything about the genre.

In blues-based rock, the guitar is primarily a melodic instrument that also provides harmonic support. The solo is the guitar doing what it does best. In post-punk, the guitar is primarily a rhythmic and textural instrument — it's providing angular punctuation and sonic color rather than melodic narrative.

This is a more radical departure from rock convention than it might seem. Most of the guitar vocabulary in rock — the power chord, the pentatonic solo, the blues lick — is a melodic vocabulary. Post-punk guitarists had to develop a different vocabulary: the sustained power chord as texture, the jerky repeated figure as rhythmic element, the dissonant voicing as color.

The interesting consequence is that the guitar in post-punk is often playing something simpler than in classic rock but achieving more compositionally. Simplicity in service of texture and rhythm can be more demanding than complexity in service of melody.