Volcanicash
Are we still doing this? Just to be clear, the original source of this infographic was Reuters Asia Financial Graphics team. Their version did not show information about earlier handshake signals. The “ping” arcs were added by an Australian designer and are simply (quote) “rough reverse extrapolation of NTSB tracks based on constant speed and track assumptions”. As has been previously noted here, the nature of these additions is clearly indicated on the graphic.
As you say, these published maps are just cartoons and don't reveal anything exact about the route derived by NTSB from the pings. The original AMSA maps showed the search area straddling two courses stated as being the NTSB solutions, but AMSA said then they had already corrected for currents since the 8th March, so the NTSB course solutions must have been well to the West of the search area. Therefore, the course lines on the AMSA maps were just sketched in to give a general idea. The fact that the search area has moved significantly to the East in the last few days may suggest the original AMSA West to East drift correction is was wrong.