Not every Linux distribution "comes with" Firefox or Chromium. They may be an option on the install disk and may even be part of the default install but they do not have to be installed and there are other choices (e.g. I typically install SeaMonkey because I like the mail client it comes with). In fact I can decide to install Linux on a PC and not install a browser at all. Last I checked it's still hard/impossible to remove IE/Edge from Windows. [1]

[1] Although admittedly the last real work I did in Windows was 7, so please correct me if the situation has changed.