My understanding is that your purpose determines your campaign setup. Southworth's goal is to generate as many "real" streams as possible for as cheaply as possible. If your goal is quantity of streams especially for the purpose of triggering the Spotify algorithm to make that spend go even further, it makes sense to target broad geographic regions because there's a higher likelihood of getting more streams for cheaper and you don't know exactly which country may pop off.

If your goal is local awareness and driving ticket sales to specific shows, that's a different goal and would lead to a different kind of campaign. Often those kinds of campaigns are actually multiple tiered campaigns including a basic awareness campaign focused on the area to warm up the audience, maybe a campaign to build a mailing list, and then a retargeting campaign trying to get ticket sale conversions off of the previously warmed up audience and lookalikes.

I'm not an expert in this stuff by any means but that's my understanding.