Writing from memory here, please correct as required, but one of the major concerns with scss style syntax was that it was "undesirable" for interpreters to differentiate between tag names and properties due to legacy CSS token-parsing techniques and the performance concerns around "infinite" lookahead ("controversial"). `color` is one example (possibly the only example) of CSS property / tag name overlap which makes the scss style syntax `tag { color:hover { color:blue } }` slightly ambiguous and potentially tricky to parse.