I recently did Cambridge-Birmingham-Stafford on an XC-only advance. The Birmingham-Stafford XC service ran over 30 minutes late, so I was entitled to Delay Repay.
Another passenger doing the journey on a walk-up ticket would have been expected to get the first available alternative service (e.g. an LNWR service), so not entitled to Delay Repay.
So I benefitted more (in repayment terms), by paying less (but got more of a delay inconvenience).
The toc benefited more from your ticket due to how the fares are allocated. As such they have to accept the additional hit when they fail to provide the service expected.