The conformal cylindrical projection with one standard parallel is named for Mercator.
Mercator's map is also called sea chart because of its great relevancy concerning navigation of seafaring.
The course of a ship is mostly fixed as an included angle to the North-direction with the aid of a compass. Thus the Course Line intersects every longitude under a constant angle, so it is a loxodrome. In a Mercator Map every loxodrome of the sphere is projected as a straight line because on the one hand the projections of the longitudes are parallel straight lines and on the other hand the projection is conformal.
The loxodrome of the sphere as the connection of two points on the globe is in fact longer than the associated orthodrome but the course on a loxodrome is easier to navigate than the course on an orthodrome. In case of navigating onto a loxodrome it is always sufficient to fix the course angle once, whereas navigating on an orthodrome the course angle must permanently be corrected.