Basically the dumb critics and audiences just wanted princess movies, so when they finally got another one with TLM after so long, they heaped praised on Disney again
That film was so very close to putting the entire company out of business so it could never be a masterpiece IMO.
Especially if you look at how much the company is worth now. It's staggering how impactful the renaissance was.
OK masterpiece is probably a bit too far - It's obviously not as good as the standards like Beauty and the Beast and Little Mermaid - but it's seriously good. It bombed because it's quite scary for a kids film and featured no songs, but its amazing nevertheless