[skookumchuck]

Any idea that comes out of a brain-storming session is de-facto obvious.

Non-obvious ideas take time to think about and develop.

[jacobolus]

In a “patent brain storming camp” people are going to (at least sometimes) bring in ideas they have been ruminating for years.

In many cases (according to the grandparent poster) ones unrelated to their direct jobs, which arguably their employer has no reason to claim rights over, but which might well still be novel advances to the state of the art.

[skookumchuck]

The ones I've seen were all ideas made up on the spot. The whole point of brainstorming is to make up ideas on the spot.