Look up two-digit date fields, packed-decimal, zoned-decimal, bitfields, and other encoded-field datatypes. All were explicitly created to save on data storage, when the main transmission medium was punch cards.
The rationalisation is not conjecture. It's fact. Bits and baud were expensive.
And that's before getting to bitshifted storage of software and similar tricks.
SABRE dates from the 1950s. Which was a long time ago in Internet Years.
The computer it was based, the IBM 7090, on had memory storage of 32,768 words of 36 bits, about 64 KB using today's 16-bit byte. It operated at 100 kflops/s. A modern AMD-64 CPU tends around 4-64 flops per cycle, or in the neighbourhood of 4-250 gigaflops/s, up to about 2 billion times faster.
I've programmed on punched cards. System/360, FORTRAN77. Carter administration.
Whether history exists or not, is not the question. Whether byte misers from long ago caused this name-mangling issue, that's the conjecture part. At least one aspect of the guy's complaint was of recent origin, and ironically that was from arbitrarily insisting the name be longer than it is.
The SE answer links to the relevant documentation. Spaces are indeed optional. It's not explicitly documented that a non-whitespaced 'MR' is read as a title, but it seems likely.
