I suppose John Lennon is responsible for the cringe-inducing confessional singer-songwriters of the 70s and beyond the same way Led Zeppelin is responsible for all those second-rate boogie and metal bands: which is sort of, but not really. The question is then: Why does Lennon's gut spilling work so well where others fail? For starters his melodies and voice are so excellent that a song like "Jealous Guy" works on that basis alone. Plus he's not engaging in humble-brag; this is not a disingenuous back-door gambit to make himself look good. And who can't relate when he says: "I didn't mean to hurt you," which is what we all say after we hurt someone we love.
Bonus question: Is it possible that jealousy is the only vice or shortcoming with no upside? I mean gluttony and greed and lust all have some pleasurable aspects that manifest before things go bad, right?