That's not the point. There needs to be a delineation between where the coast ends and the water begins. It can be a border or the water can be a different color, doesn't matter.

I just clearly told why I think it is bad practice, it makes it impossible to tell how forested the coastlines are.

I don't think that's helpful or even looks good. If the point is so people can see where there are and aren't forests, now you can't because the shoreline just melts into nothingness. It's really bad practice to use a color that will fade into your background.

The water needs a different color or you need a border, Chile and Bolivia just dissolve and you can't really tell where the actual border is.