My recollection is that the “intentionally flawed Jedi” idea evolved from fan discussion/debate on the Internet in the early 2000s, stemming from early criticisms of the Prequels. I remember SO many conversations on various old-school web forums that went something like this:

Person A: OMG the Prequels suck so bad, why didn’t the Jedi ever send anyone to rescue Anakin’s mother? It literally would have taken them a few hours to pick her up from Tatooine. I mean Qui-Gon wanted to do it anyway but couldn’t at the time, so why didn’t anyone just come back for her later?

Person B: OMG you’re so stupid you don’t understand George Lucas is a genius. Did you even WATCH the movie? The Jedi are SUPPOSED to be shown as flawed - they didn’t want Anakin to have any attachments so that’s why they never went back to pick up his mom. Idiot.