Why it matters to a buyer
Because Google indexes what its mobile crawler sees, a site that hides content, navigation links, or structured data on its mobile layout to save space is quietly removing that material from what Google can rank on, even if the full version exists on desktop. A buyer reviewing a responsive redesign should specifically check that nothing important, like a full product description or category links, was trimmed from the mobile experience for the sake of a cleaner phone layout.
How it is measured or applied
Sites are checked for parity between mobile and desktop: the same primary content, structured data, meta tags and internal links should be present and crawlable on both, and images should carry proper alt text and lazy-loading that does not hide content from the crawler. It is diagnosed using Search Console's URL inspection tool, which shows exactly what Googlebot Smartphone renders for a URL, and by manually comparing a page's mobile and desktop versions for anything present on one but missing from the other.
Sources
- Mobile-first indexing best practices, Google Search Central
