Apologies in advance for taking this thread off-track, but:
In a hypothetical scenario where I’m running my own business I would be very hesitant to open source my product before having built a solid customer base and even then I would be second guessing that decision. For more details around what potential issues one might run into when open sourcing their product I would suggest reading up on the struggle that Timescale and MongoDB went through.
If I understand correctly these companies went through these issues partly based on the fact that they originally had very permissive licenses. With the GPLv3, that would be less of a concern. In fact, Mongo even says, in the FAQ you linked to, that their new license is based on GPLv3.
From this point of view GPL might also be an issue since it will scare most (all?) companies away from using it.
This might actually be a desirable outcome Seriously though, if any company genuinely wants to use this library, they will do what any reasonable company would, and ask the author to sell them a commercial use license.
This might lead them to develop their own alternative and license it under LGPL, MIT or the Apache license which all are more business friendly while still forcing any modifications to be available.
Unfortunately for the OCaml community, till date we have not exactly seen companies busting down the door to publish libraries (with a few notable exceptions of course). It could even be argued that companies actually paying attention to and participating in the OCaml ecosystem could only be a good thing, and if the author of this library played any part in making that happen, I would just have to say, hats off to them!