We at Musicmusic always prefer the real synthesisers over softsynths. However Arturia managed to do emulate the Moog Modular with it’s 9 (!) oscillators for €229,-.  The real deal goes for over 30K now. Although this softsynth wil never sound like the real deal there are a couple advantages:

With the original extremely expensive Moog you couldn’t play more than one note at a time, so you needed to build things up with multiple takes and a tape recorder. Also you can save your presets easily with the softsynth version, which makes it easy to switch between sounds. Not to mention this version weighs as much as your laptop.
Originally, synthesizers weren’t seen so much as music instrument replacements, but as taking things somewhere else. Even in the seventies, some university would not allow a keyboard to be connected to their Moog, because then it would make it too easy to fall into the habit of using it as a glorified organ.
Even when synthesizers got small and used switches rather than patch cords to rearrange the modules (and usually then limiting the variety), they were seen more as for adding some unique sound to the stage rather than to emulate other instruments.

Now, synthesizers not always mean “electronic music” but a means of getting all kinds of instruments into one package, and with a single interface, the piano keyboard, to control it. In the 70’s some folks trucked their Moog modulars on tour. The drama of patching things mid-song onstage and the faux-scientist tweaking of this 3″ high sea of knobs went a long way toward elevating the prog rock keyboardist to wizard status- see Rick Wakeman, Darren Emerson (see pic.), etc.
The modulars were used for sound effects/noise sounds as well as lead synth sounds. A good Moog modular makes a very nice noise, and for some they were irreplaceable onstage. Because they were so large, heavy, and unreliable, you had to be a major touring band with a good synth tech and sympathetic roadies to do this, but it certainly happened pretty often.

Later came the MiniMoog,  Moog’s attempt to make a playable, basic synth that was more portable. It was extremely popular with touring acts, but of course, didn’t offer the crazy modulation and processing options that the big boy did.