There were a number of instances, however, before computers, where even a piano wasn't enough and a compsoer had to do some demos with an orchestra (which even still hapens today, to a far lesser extent).

The New Number 2: "Are you going to run?"
Number 6: "Like blazes. First chance I get."

And in general I'd say standards of craftsmanship were dramatically higher in the so-called "golden age" than they are now, probably because there are so many composers in the contemporary era who use MIDI controllers and sequencing programs as a substitute for a genuine understanding of harmony and counterpoint.
Indeed. And the first time the composers and directors/producers heard their music was on the recording stage. Everything before was "piano only". So no endless mockup sessions, approvals, and rewrites. Directors trusted their composers.
And they had to "lock" their film for recording, so no endless re-cuts and re-recordings either.
And composers had to use their imagination instead of listening to instant mockups of their output, which from my own experience is detrimental to the composition process.
No, Schmuck! You are only entitled to your INFORMED opinion!!
Harlan Ellison

3. Miklós Rózsa (he was admired by Bruno Walter and famously inspired Jerry Goldsmith to become a film composer)
   You're right about Williams. I will also put forward that Rosza's
   Julius Caesar
   is the greatest film score ever in terms of atmosphere and utmost technical mastery of the orchestra.
   "Man was meant to grow, not stop!" -Robert Browning

Here a few people that would be considered "composer's composers":

1. Erich Wolfgang Korngold (Mahler, Puccini, Richard Strauss, Saint-Saëns, Sibelius, Humperdinck, and many others believed he was the modern Mozart; so I'd certainly say that amongst the luminaries of film scoring, he was the ultimate "composer's composer")
2. Max Steiner (he studied with Brahms and Mahler)
3. Miklós Rózsa (he was admired by Bruno Walter and famously inspired Jerry Goldsmith to become a film composer)
4. Franz Waxman
5. Bernard Herrmann
6. Jerry Goldsmith
7. John Williams (he's really the most technically skilled living composer in any genre of music)
   And in general I'd say standards of craftsmanship were dramatically higher in the so-called "golden age" than they are now, probably because there are so many composers in the contemporary era who use MIDI controllers and sequencing programs as a substitute for a genuine understanding of harmony and counterpoint. Hans Zimmer and his Remote Control Productions clones are the worst examples of this ongoing trend. These technological enablers and lazy attitudes have decimated the industry to the point that Williams has ended up almost by himself in carrying on the values and collective wisdom of the previous generations of film music masters.

John Corigliano
Leonard Rosenman
Gabriel Yared
Shirley Walker
I remember two different composers commenting on
Walker
in interviews how taken aback they were at her ability to not only write but sight read & play. Serious musicians have such and more capabilities.
It probably goes without, but most of the old school composers were cut of such cloth.

The New Number 2: "Are you going to run?"
Number 6: "Like blazes. First chance I get."