I have a different perspective. Let me first say clearly, that I reverence nature and want to see her remain pristine. But I also understand that humans need a way to express themselves in certain emotional and stressful circumstances. When we have those experiences, having a common structured personal expression, such as flowers at Buckingham Palace when Princess Diana died, it can be quite a healthy personal expression as well. We are beginning to focus, indeed, however, as well, on the cost to the environment of such rituals.
Nevertheless, In my opinion, eliminating Cruz de Ferro would be a mistake! Placing or replacing a rock,or taking home someone elses prayer as a personal prayer could be a responsible outlet, and not too costly a consequence, at this time in our history for our environment and helpful to pilgrims.
If we could focus on eliminating the boots, tampons, plastic bottles, toilet paper, and other trash along the way it would be helpful. Providing periodic places for sanitation disposal along the routes would help the environment as well. I am a proponent of leaving no trace, but the garbage has to go somewhere, and having more services along busy routes like the CF, would eliminate some of this trash. It is not like someone is in the middle of a 3000 meter mountain, after all. To finance the garbage pickup and some portable waste places, a fee to everyone staying overnight somewhere on the routes..like 50 cents a night or more, or whatever would be needed to finance the cleanup, would go a long way to keeping the paths clean.