SF is a writing style, not a set of technologies. Hence why Neal Stephenon's Baroque Cycle is SF despite including no SFnal technologies (except maybe an allusion to just one), and why The Time Traveller's Wife is mainstream, despite being about time travel, the most outlandishly SFnal concept there ever was.
While I basically agree with you, the literary nazi in me must say that SF is a genre, not a writing style. The Baroque cycle crosses the historical fiction and SF genres into a lovely mutant child that could be called Historical Science Fiction. The Time Traveller's Wife also crosses genres, with a heavier focus on the Romance than the SF.
