I think my point was more that the author is the only one who can legally make closed-source modifications, i.e. their open core business model, giving them an unfair advantage. Also, the FUD surrounding AGPL. I guess I'm trying to point out that there's an obvious reason every open source business uses AGPL... and it's not that they want competitors to contribute back.

Competitors likely have the resources to figure out how to be compliant (with or without giving back), so that's not really it. And as far as I understand the startup situation, most struggle to attract paying customers at all. If you are in a situation that someone is competing against you using your own codebase, you have already gotten very, very far.

I believe the usual AGPL idea is that it generates sufficient FUD for regular customers so that they don't want to run the free (AGPL) version in production. Instead, they feel compelled to cut a separate, commercial licensing deal. A project/product is likely to follow thus model if the nominally AGPLed project has a contributor licensing agreement that involves an asymmetric copyright grant (i.e., contributions are under a very permissive license, but you only get the aggregate of all contributions under the AGPL).