DotA has bad coding because of their bad algorith,slow codes,etc,not because it leaks or whatev.
IceFrog team(yes,its a team) didn't do anything in DotA2.They left to job to Valve,and Valve just copied and observed how DotA works,they implemented it.
0 Leaks was just a reason why DotA has a smooth gameplay. And not just that,they're balancing was a god-like.
Actually,due to my discoveries,some DotA dummies are still selectable these days,notable was the Light Strike Array by Lina,which has the Shade icon.
DotA has very simple code,that's why the gameplay is very smooth and efficient