Range hood vents into attic space
Regardless of if this was ever standard, it's a bad idea.  I lived in a 60's built house and the dryer vented under the house from a hole in the floor.  The lint and moisture issues there were pretty bad to say the least.

The same issue is happening in your attic (crawlspace?).  The moisture in the exhausted air can cause problems for sure.  The air can also contain grease and other contaminants that will build up and cause... general grossness.

It's true that if you don't use the hood very much, it might not be a big deal, but if you want to to be done right, it needs to be in a duct from the hood, all the way until it exists the house through a wall or the roof.