There are many ways in which ISO files are useful. You have native support in Linux and Windows (you can mount). You usually also have support in virtualization

There are many ways in which ISO files are useful. You have native support in Linux and Windows (you can mount). You usually also have support in virtualization or emulation software like VMWare Parallels, VirtualBox, HyperV… So I get it Etcher for someone who wants to do it on a USB stick is probably as easy if not easier than using cat or dd. I reckon I can probably create the ISO file with Etcher too. But I’ve installed countless distros and never had to download Etcher since I could always point the virtual CD to an ISO file. Bonus point. I don’t need to learn anything about file systems and partitions and block sizes… it just works. I have no idea how these bootable medias work since I never had to make one.