In fairness, I've done far less 'valuable' segments than CPT-JNB on DONEx's. It just depends on what you need on the ticket. Typically my low value segments have been inside the US, where the segment allowance is higher anyway and sometimes I might only use 14 of my 16 allowed segments because that's all I need. So similarly, if someone else thinks that they're not really 'wasting' a segment for a flight that might be $200 in business class paid in cash, then so be it.

For a lot of us, the entire ticket is the end goal, but there may be some segments on it that are for other reasons.