Just my two small cents: soft keywords have a cost as they make everything around them more complicated in

the parser. For example, creating custom error messages around soft keywords is one or two levels of magnitude

more complicated as sometimes you need to parse segments of syntactically invalid code, with some generality

(like "starts with this token and then anything can follow until this other token"). Soft keywords also make

highlighters' life more complicated as it has already been discussed.