Earlier quoted context omitted.
IMO compatibility issues are the result of conflating a CLI with a scripting language. If a script was written for bash, run it with bash, not fish or zsh. I can withstand having two shells installed.
You can, but if Fish's value proposition is ease-of-use, then people who can't withstand that need to be able to use fish easily still. Not being able to run `PORT=5000 yarn start` or `make && ./a.out` or whatever snippet you copy-paste from the web without understanding are going to be a big pain point for newcomers to fish. Don't get me wrong, I'm a happy fish user myself. But breaking backwards compatibility with…
fish: Unsupported use of '='. To run 'yarn' with a modified environment, please use 'env PORT=5000 yarn…'