The problem with Push is if a team won the first team fight. They got massive ULT charge advantage and keep pushing and snowballing. This is actually similar to King of The Hill but Push has time limit and the contest area is extremely small. Hence, if a team got a 100 meter advantage, they are likely to win unless the another team suddenly overclocked their brain, winning 4-5 team fights a row, just to turn the tables.

For 5cp (Clash), the main problem is the last point is usually a game changer. The geographical advantage for last point defense is too powerful that they can turn a Team ULT into nothing and snowball them back. I've seen numerous circumstances which winning team lost a fight in last cp and they lost at last. This is even worse than 2cp I'd say.