+1 It is a crowd pleaser

The "best 5", the "worst 5", the "oldest 5", the "(pick a category) 5"........ it's basically nothing but dumbed down page filler to keep print magazines going. Who knows?
Maybe the average black plastic rifle oriented magazine reader is content to accept that there are only 5 double rifle cartridges in existence......because the "expert" says so.

IMO, an odd choice to include the .416 #2 Rigby, likely very scarce at the range or in the field.

- Mike