Something that also happens in languages like C and Go, while C has the same reason as Fortran, given the limitations of their early compilers, Go has no reason for single letter receivers.

I second this. When I worked on some older Fortran codes, I had to keep a cheat sheet for the variable names and what they meant or controlled. It definitely made the code hard to read.

Yeah, this isn't the case for any codes written since may be the 00s or even the late 90s, although I admit I haven't worked on a code that old recently.