The problem with the HTTP header is that it reveals details about which www server you're running to the user, who may be a potential attacker. This makes it easier for a potential attacker to select tools with which to attack you. Apache and Nginx (and most likely other web servers) offer config settings which disable emitting information about the software and version in use. There are other ways to guess the software/version but it becomes harder.
This is an actual security problem, not some issue of feelings.
Your "worldview" doesn't seem to extend past the end of your own nose.
what is your startup going to do to generate money if you perpetuate the belief that no one should pay for anything?
I never claimed that no one should pay for anything, and I wish the people working on Caddy the best of luck. I think it's a fantastic piece of software and, as I have said several times, I am very grateful for the effort that has been put into making the project what it is.
However the change means that I have to act or be left with an out-of-date internet facing server. If you cannot see why I am annoyed at being given no choice but to spend time or money on solution because Caddy has introduced a new commercial licence, then I will not convince you of anything.
You can also pay-the-man. That's an option, too. Personally, if I "really [did] appreciate the work [mholt] and others have put into Caddy," I'd be doing that long before I go switch web server stacks, because wow that's not a lot of money if I'm doing anything where I actually care about a HTTP header, but I prioritize not freeloading where I can so that's probably "just a worldview thing".