Featured Snippet is a highlighted search result that attempts to answer a query directly on the results page.
It matters because technical issues can prevent great content from being discovered, rendered, indexed, or trusted. Strong technical foundations protect rankings during redesigns, migrations, content expansion, and platform changes.
Example
A search engine may extract a concise answer from a relevant page into a featured snippet. Publishing a clear answer helps the reader, but adding a heading or a fixed word count does not force the search engine to select it.