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.
This is simply wrong.
Is you release software that YOU OWN as AGPL, there is nothing stopping you from also licensing it as non AGPL, for a fee, in the future. I’m fact this is more possible with AGPL, since it disallows Tivoization.
If there’s a chance you want to make money off of it, AGPL is 1000x better than MIT. Once you release under MIT, a corporation can take it and do anything. If it’s AGPL a company can take it and do anything once they negotiate a license for it, and pay you for the privilege.