Greed
Corporate greed has no bounds.
I've seen similar clauses and simply told prospective employers to remove them, the same with non competes and similar bs. In all instances they agreed to do so, but this was unnecessary hassle.
Now, this is one of the reasons workers go independent and start their own software business and that's why we have IR35 changes, because those big software companies didn't like it, so they lobbied government to limit such a way out.
We are just a cattle, commodity now.