For a decade, the business case for schema markup was star ratings and recipe cards in the results. That case weakened as Google withdrew and reshuffled rich result types, and plenty of teams quietly deprioritized it.
The case has strengthened again for a different reason. Systems that generate answers rather than lists of links need to establish what an entity is, what it offers, where it operates, and how it relates to other entities. Structured data states all of that explicitly instead of leaving it to be inferred from prose.
In practice a small set of types carries most of the weight. Organization and LocalBusiness establish who you are and where you operate. Service describes what you sell. FAQPage maps questions to answers in a form that is trivially extractable. BreadcrumbList communicates hierarchy. Everything beyond that is usually optional.
Schema does not make you rank. It makes you legible, and legibility is increasingly the gate.
The failure mode is markup that contradicts the visible page. Declaring an FAQ that does not appear in the rendered HTML, or a rating with no reviews behind it, is worse than no markup at all, because it establishes that your structured data cannot be trusted.
Validate against the visible page rather than only against a schema linter. A technically valid document that describes a different page than the one users see is still wrong.
