They are getting down voted because their choice of stack (the set of software that was chosen for use in developing an application) is being used as a means to absolve themselves of the responsibility of supporting the last available cross-platform alternative to anti-consumer, chromium based shit.

If they had just not mentioned it or said they just don't like Firefox, there wouldn't be down votes.

Anyone is free to use whatever they want, but the comment you're responding to is just a shit take.

My last job used a stack that was unfriendly to Firefox, but I still used Firefox as my main development browser so I could catch issues and work toward better interoperability.