It generally got a bad reputation because it was abused to keep people on portal-like and aggregator sites. These sites would parasitically add navigation banners and ads(!) to content they didn't own. You had to be somewhat web-savvy to know how to escape an annoying frame.

They also wouldn't fly these days because of CSP and general web security.

When Google Image Search first launched, it surprised people because they found a legitimate use for frames that wasn't user-hostile.