The use case allows marketing agencies to identify Law firms which have Google tag manager installed on their website.
The absence of Google tag manager would mean that they have never tried an ads campaign and if they are getting significant organic traffic, they might be interested in an Ads campaign or another channel.
Alternatively, if they are running an ads campaign and do not have Google tag manager installed, they might not be running it very professionally.
All of this indicates that these Plumbers are actively reconsidering their marketing activities.

