node changes in hook_validation

in contributions\docs\developer\hooks\node.php, the description for hook_validate reads :

It can also be used to make changes to the node before submission, such as node-type-specific formatting.

I would like it very much to be true, but according to all my attempts, it is not.

Besides, all hook_validate functions in core (that is, node validation hooks, not form validation hooks...) are declared with :

function whatever_validate($node) {
...

and not

function whatever_validate(&$node) {
...