Disclaimer: I did not read past the 1st page of comments.
Just chiming in to say that what Hunt is claiming is true. Higher volume mean more bead stress at the same pressure.
I can see someone who is not so familiar with tubeless making the OP’s error. Being a bit more familiar with this stuff I would not pump a 38mm tire up to 80psi tubeless unless I had some clear documentation that both the tire and rim could handle it. I almost reached to plug my ears and shield my face when I read your opening sentence.
I do think these things need to be more well and explicitly labeled right on the rims, the same way max tire pressure is labeled on tires. It should give max pressure at a few different tire sizes. IF the rims just say “100 psi max” that is misleading , IMO.