Yeah, Pakistan really benefited from South Africa's defeat against the Netherlands. Each of the other teams has done well to reach the semi-finals. The Pakistani team was lucky enough to reach the semi-finals but gradually improved as the tournament progressed. Due to their middle order weakness, everything was shattered.
Actually their middle order and lower order was performing well in the initial phases. Back then the main issue was that both the openers (Mohammad Rizwan and Babar Azam) were scoring too few runs, and that too at a very slow pace. And then the injury to Shaheen Shah Afridi removed the venom from their pace attack. On top of that, the spinners were struggling in Australian pitches. And then Babar regained his form when it mattered the most. But the team balance was not there. One or the other component was always performing poorly. England on the other hand had good team balance.
Pakistan has been playing extremely good cricket before world cup ,recently Pakistan won triseries against Newzealand and Bangladesh and before that Pakistan won in T20 series against England and before that Pakistan was the runner up in Asia Cup (Sirlanka won) . So no one can say that Pakistan is a weak team and its batsman are not performing, yes there comes a time in all cricketers life in which they perform badly or you can say out of form so that is their time now. They'll regain their strength and come back stronger.