You' right about IROPs being treated the same way but some airline agents are still more likely to try and pass the buck in complexe situations.

The last time I bought a ticket on an OTA was to the Middle-East one PNR, two different airlines. The last flight from Europe to my destination got canceled: the OTA told me to deal with it at the airport bur at the airport I was told to contact the OTA by the airline taking me to Europe ( and whose name was on my CC bill). Took one hour to get sorted out. If I had an airline issued booking I could have called reservations and they would have rebooked me instantly.