The issue is scummy companies like cloudflare which are causing these issues. If your software is blocking legitimate users then your software is shit at its job. It's not the users fault.
If on the other hand unsubscribing from mailing lists is not the true use case and we are actually being asked to help a bot bypass safeguards… then Cloudflare is doing a great job here.
But if you're going out of your way to look suspicious (ie. "I use a heavily customized Firefox config on Linux"), surely you'd agree at some point it goes from "your software is shit at its job" to "it's your fault for looking suspicious"? If you walk into bank wearing a balaclava and get stopped by security, it's not really "security is shit at its job".
Seems like a slippery slope argument, but isn't reflective of reality. They still allow Tor browser to pass, of all things.
But if you like: the arbitrarily blocked user if not at fault, cloudflare is at fault.
That doesn't advance the conversation, or show that cloudflare should be always as fault, as you seem to imply. Even if people are pro privacy/freedom, I think most wouldn't give the individual (as opposed to the security provider) unlimited leeway, as seen in the bank example.
But banks aren't mandated to admit you either. Just because it's legal, doesn't mean a private establishment has to let you in. When it comes to denying entry, banks are relatively tame. Some establishments go beyond that, by denying entry unless you wear formal clothing, or presenting proof of identity.
Of course it'll be presented as a security feature, because users are dumb, whilst also allowing vendors to lock you into their ecosystem; similar to how passkeys are currently being push by these same companies.