I wouldn't say that's true. Recently I was delayed on SWR meaning I missed the last GTR connection back home. SWR lines had shut by this point (almost 1am), but GTR Twitter called SWR control on my behalf and worked out the best option to carry me home -- a later GTR connection, then a taxi for which SWR would reimburse me for.
I will say that I have also (almost) been left stuck at Farringdon after the last train southbound has been cancelled, after which GTR offered me a taxi from Farringdon for the full 42 mile long journey home. I managed to kick myself into gear and get the train 15 mins earlier which was running fine, in the end.
GTR have always been very eager to help me in the past, no matter what the issue is. Well, maybe besides PRO alternative transport during strikes...
Then again, I was 11 when FCC was taken over so I never got to experience their customer service first-hand (at least not in any way I can remember).