Acton has an active public trail system incorporating rock pile sites in two or three places, with interpretive panels. It is called the "Trail Through Time" (TTT) and is the result of efforts by Linda MacElroy. Please see (http://ttt.connactivity.com/)
The sheer number of sites (roughly one per every 5 minutes as you walk along) is a factor, as is the popularity of the trails. Anyone seen harming sites along this trail system is likely to get visited by the police; and the neighbors are proud of living near these interesting archeological features. I have not heard any horror stories and, as far as I know, the TTT program is expanding to incorporate other sites, as opportunity permits. Acton and all adjacent towns are full of sites, and they are going to get connected together eventually.
I see no reason why the National Parks should not be doing exactly the same thing.
I invite you to look at Google results for the search terms "trail through time acton ma" [but leave out the quotes]. The Acton sites now have their own Wikipedia entries. That is what public awareness and stewardship look like.
ADDED: You can see that the new (non yellow) trails reach into adjacent Carlisle. I don't know about signage there but I do know those new trails go through rock pile sites.