Is that somehow inaccurate?
I can certainly see an advantage of implicit typing if I’d be writing my program by hand on a sheet of paper to be passed on to a keypunch operator. Besides saving myself writing, it also saves typing for the keypunch operator. I would probably keep a list of variables and their meaning on a sheet of paper, placed on the side. Today MATLAB calls this the “workspace”.
If you look at the IBM 1130 page on Wikipedia, it states
Much user programming is done in Fortran. The 1130 Fortran compiler can run on a machine with only 4,096 words of core—though the compiled program might not fit on such a machine. In this multi-pass compiler, each “phase” processes the entire source program and takes it another step toward machine code. For example, the first phase reads the source statements into memory, discards comment lines, removes spaces except in text literals, concatenates continuation lines and identifies labels. The compiler is available in a disk-resident version as well as on 8-channel punched paper tape or punched cards.
4096 words - thats’s 4 KB (assuming 1 word = 1 byte). The fpm tarball is 149 KB, we could run it through FixedFormForever and see how much it shrinks.