Here's a clip of Chris Collins. He describes forward pressure in Chi Sau, and how you should train this with a partner. Simple, LTWT, as it is taught in Hong Kong. Nothing illogical about it.
Maybe its different to the WSL method. Maybe it's different to PB's interpretation of the WSL method. But the method being shown here, and the simple idea behind it, is the way LT has taught it since having lessons with YM and having opened his own schools in Hong Kong.
https://www.youtube.com/watch?v=W_JO8QEabjI