EDIT: My mistake. I hadn't thought of right clicking the individual markers on the menu on the right. I still think an overall "Toggle All Markers" button would be convenient, but this serves the purpose well enough. Special thanks to akpak for actually explaining how it's done!
I, and, judging from a quick search of the subreddit, many others have been hoping for a toggle on the map to enable or disable map markers since day 1. There are many points of interest in this game that are worth marking, but this results in the image of the landmasses themselves becoming totally obscured by markers and text when zooming out on the map. This problem is even further compounded by the cartography table, as now I have all of my friends' markers cluttering up the map along with my own. A simple toggle added above the one for the additions from the cartography table would do wonders to solving this issue, allowing us to turn the markers on and off at will to view the map underneath at any zoom level. Pretty please, Iron Gate!