First of all. Your questions are not daft and have sparked fun and interesting discussion, so don't stop.
I am in the buy-what-appeals-to-me camp. Sometimes with fabrics that go along and sometimes not. I find resisting fabric difficult although I am trying to use up my huge stash before I buy much more.
But I am also the queen of remnants. They are considerably cheaper than yardage and I like scrappy quilts. Or I gather a number of remnants over time that coordinate and make a non-scrappy quilt.