Howdy 411A, been a while.
If you get to your decision point and decide, yes I can make DXB with just alt fuel plus fixed then you continue. The point these guys are making is that no delay at DXB means up to 20 minutes. So as you descend into DXB you start to get vectored all over the place and now you have lost your alternate fuel, ie you commit and say to your self "gee I didn't see that happening" But in fact you accepted it as a strong possibility a couple of hours previously at the decision point.
And I know EK will never be as good as your beloved GF was back in the 80's but they have been using reduced reserve planning from the start, with the 310s/300s to LHR with FRA as the enroute alt and in more recent years with full 330s in winter from MNL. Its just that in those days, no delay meant just that.