This largely matches my experience working with a team internally who were trying to get Backstage deployed. Or maybe I should say they got it deployed, the lead dev in charge left, and now it sits there mostly used by interns and completely un-serious people who’ve still got the idea that someday it’ll turn into this amazing must have tool that everybody will suddenly adopt.
One of the biggest problems is that they didn’t try to actually interface with other teams to sell why Backstage might be something they want to use. Instead they got it 20% populated with low hanging fruit, and the rest of the company is blissfully unaware that it even exists.