Following SEO best practice produces a worse page when the practice is applied mechanically against the specific context instead of with judgment about whether it fits. Best practices are defaults built for the typical case, and a real page is rarely the typical case in every respect. The damage comes not from the practices themselves but from treating them as rules that override what the particular query and answer actually need. The moment a default contradicts the specific case and you follow the default anyway, the page gets worse in service of a checklist.
The cases are recognizable once you look for them. Forcing a number into a question that is not numeric distorts the answer. Padding a page to a target length the query does not want buries a short, complete answer under filler. Stuffing keywords into prose that read naturally before makes the writing clumsy and worse for the reader. Adding an FAQ block that only repeats the page pads without adding. Matching a format the answer does not fit, a table where prose is clearer or a list where a paragraph belongs, fights the content. Each is a sound default applied where it does not belong.
This contradicts the comfortable assumption that following best practices keeps you safe. Safe is what they are on average, not in every case, and average is not where any specific page lives. The pivot is best-practice-applied-without-judgment. A practice that helps the typical query can hurt the atypical one, and a page that satisfies a searcher poorly while ticking every optimization box has been made worse by the very rules meant to help it. The defaults are a starting point, and the specific case is the thing they exist to serve.
To avoid the backfire, treat each best practice as a default to weigh, not a rule to obey. Before applying one, ask whether it serves this query and this answer, and skip or adapt it when it does not. Lead with a figure when the answer is numeric, match length to the query’s real need, keep the prose natural, and choose the format the answer fits. Apply best practice with judgment for the specific case.