People who use GPLv3 want the code to stay open/libre under any circumstances. If this is the goal, why not use the AGPL instead, even for applications which are not served over a network?
This takes away the possibility that people integrate parts of your program into a proprietary network application, even if this seems improbable. There’s nothing to loose with using this license, but potentially some gain.
Only reason I can think of is that AGPL is less known and trusted which may harm adoption.
I may or may not care whether the code gets integrated into a proprietary network project, depending on the particular FOSS project. If it’s some general purpose command line widget, for instance, I would probably prefer not to restrict its usage in that context. If it were a long-running back-end online service project like MongoDB, though, that would be a different story, because that’s the kind of thing AGPL was created for.
GNU licenses aren’t about denying people from making money, they’re about ensuring that they share their code changes with everyone. AGPL was created to solve a new edge case concerning SaaS companies like AWS, Azure, Google, Alibaba, etc.