> It's funny to me to see the same people who complain about sigils in perl whole heartedly adopt the Rx convention of naming streams with a tailing $. It's literally just a sigil.

This one is a naming convention. Same as how the previous generation of javascript developers used to prepend variable names with a dollar sign if those variables referred to jquery-wrapped objects. Same as starting class names with a capital letter, or using all capitals to name constants. It doesn't have any special meaning for the parser. Your program won't break if you don't follow these naming conventions. It's entirely a style thing.