Because my success (however I define it) might've had nothing to do with XYZ. Maybe it just happened to be that the editor needed one more story for that "Enchanted Car Washes" issue, and bam! I just happened to send an enchanted car wash fic. Maybe an agent thinks that novels about enchanted car washes are about to become the next big thing, and there, I win again.
I think there's a big tendency in the writing world for us to say our rejections were just a matter of taste or bad luck and our successes were because so we're awesome that no one could resist us. And that feels good as long as the successes keep coming. But I don't think you can hold those two conflicting ideas in your head all the time, especially in the face of a long string of rejections. Either you're going to come to the conclusion that everything is luck or you're going to come to the conclusion that you just don't write well enough. The latter is a great way to shake off Golden Words Syndrome. But there's something horribly demoralizing about seeing self-improvement, getting hit with more rejections, and then getting told by someone that said rejections just mean you're not good enough. Now, I don't think getting published is totally luck-based. I do think putting your manuscript in Times New Roman rather than Wingdings helps your cause. But outside of the basic advice to not be a creepy idiot and to write in competent English, I think just about anything else goes.
All you can do is try stuff and if that doesn't work, try other stuff. Don't discount the improvement you see in your day-to-day writing, even if you're the only one who seems to notice it's there. Go that way really fast. If something gets in your way, turn.