The claim
Correctly implemented, guideline-compliant structured data is a prerequisite for many rich result and enhanced-appearance features in Google Search.
What the evidence shows
Google's structured data general guidelines and feature guides make clear that markup must be valid, match visible content and follow feature-specific requirements to become eligible for rich results such as reviews, FAQs, products and breadcrumbs. Eligibility is not a guarantee of display, but invalid or spammy markup removes eligibility entirely.