See bug 1906260[1] for more details but I am planning on removing the -no-remote command line argument from Firefox. This has been unneeded since Firefox 67 when we started supporting running multiple profiles simultaneously without it. The only effect right now is often to cause some user confusion as many tools and websites recommend its use. In the future its use will break some new functionality we are adding with the new profiles work. We will retain the -new-instance argument which bypasses the startup check for other running instances using the same profile which is essentially the same thing (though you pass this argument on subsequent instances rather than the first instance).Please let me know if you know of any reason not to remove this.