Why repetition is the signal
A job description is written by someone circling the same few things from different angles. If reconciliation turns up six times — in the summary, the responsibilities and again in the requirements — that is the job. If Jira turns up once in a list of tools, it is a nice-to-have. A matcher that scores both as one point each throws that difference away.
Say a posting yields 40 terms and your resume covers 24 of them. An unweighted matcher calls that 60%. Paste in three passing mentions — a certification named once, a tool listed in brackets — and it reads 67%, though nothing about your candidacy changed. Here those three carry about two per cent of the total weight, so the score moves by two.
The score is matched weight divided by total weight, and the total is fixed by the posting rather than by how much you paste. A longer resume cannot inflate it. The only way up is covering the terms the employer kept returning to.