Back in the day, my university would load balance based on the browser being used. When results were released every semester, all you needed to do to switch to the fast lane instead of contending with other students for resources was jump on IE (or even spoof your user agent). None of this was public knowledge.
I say this just to make the point that people do all sorts of weird stuff with web infrastructure. The inferences made in this privacy nut’s blog post seem a bit off the cuff.
Absolutely not, it is not reasonable or expected that a credit card company launch a website that doesn't work with Firefox.
> Back in the day, my university would load balance based on the browser being used.
What on earth?
To your specific point about just moving elsewhere, complaining in public about bad industry practices is part of Capitalism and part of how consumers regulate the free market. "Take your business elsewhere instead of complaining" has never really been how this has worked; businesses don't get to opt out of being shamed just because they have a cancellation form, and they shouldn't have any expectation that users will or should be quiet about their bad business practices. The free market is not a replacement for criticism within social spaces; the free market works alongside that criticism and is reinforced by that criticism.
Public complaining is an essential part of how consumers within a free market coordinate with each other and educate each other about abusive corporate behavior, and it serves as an additional mechanism alongside boycotts and cancellations to help punish bad actors in the market.
Oh well, what can you do? Vote with your wallet. Tell everyone on HN and Reddit. I agree. But at a certain point it wastes too much of my energy, so I'll basically just cancel cand tell them I can not use their service because reasons, very disappointed, bye.
Sigh
In terms of being blocked by CloudFront (not cloudflare),I actually got a website to fix their policies by just emailing their tech support and showing that simple user-agent changes bypasses their policy anyhow.
Firefox on Android was still working, though, loathe as I am to put passwords of any significance on my phone. Doesn't directly address your question, which I'd like to know the answer to as well.