Holey crap! Seriously? That seems a little excessive.
For OUPV requirements, the CG makes a distinction between "Inland" (close to shore) and "Near-costal" (out to 100 nm). They define their own boundary line between the two, which varies in distance from shore by region, but in my area on the West coast of Florida, "Near-costal" waters are generally about 12 nm out. I don't recall if they have a different catagory for "way the heck off shore", but I suspect at that point you get out of the world of recreational boating and into the Masters License and the 200 nm line that Welder mentioned previously.
Where ever the line is, it just surprises me that the recreational boating community hasn't developed some set of generally accepted practices for the extra gear and procedures that are prudent for venturing offshore. What's appropriate for different distances and situations seems to be largely based on tribal knowledge and the individual captain's tolerance for risk, and is learned over time based on trial and error. Trouble is, without some general guidelines to go by, inexperienced captains may be putting themselves and their passengers at higher risk than they understand as they push the limits of their own experience.