Land owners can put pressure on local government to change anchoring laws which are essentially federally mandated. But unless boaters are breaking laws and regulations both on the water and in abusing land access, the landowners don't have a leg to stand on.

The problem looks more to me, people abusing our privilege to navigate and anchor in federal waters. When boats start setting down roots as housing at anchor, especially in anchorages in populated areas, they strain the capacity of the anchorages and shoreside access.
There are mooring and dockage areas available that allow that and take the shoreside strain into account in charging those boats their fair share of the services we all pay for.

When an anchorage turned floating community gets bad enough, this gives land side pressure some legal clout to impose(perhaps illegally, but who's going to oppose it legally?) local regulations against the right to anchor. This will always be a legal issue on some level I'm afraid, and we're(boaters) as much to blame as the land owners, IF we continue to defend those that are turning our anchorages into permanent housing areas.

In defending this anchorage abuse, we're taking away the very maritime traditions that drew most of us to sailing and boating to start with.