Entryway has that dark early 1970's paneling.

I've finally decided to get rid of it, so I did a little exploratory
surgery to see what kind of a project it will be.

The good news is the paneling isn't glued to the drywall. It'll come
right out.

The bad news is there is no drywall. Someone put up homasote board
underneath the paneling.

Is this common?