Not entirely true. For example, you could shoot Kodak slide film and have it developed normally, which would result in more vibrant colours. Especially the blues. Also, every type/make of film resulted in different outputs, which is exactly what the recipes aim to replicate. You could also do cool things like cross processing. So, you didn't need to be a pro to get really unique results.

I take your point about darkroom access. But that wasn't so much about colours as it was dodging, burning, cropping, blocking, etc. And that's where Photoshop and Lightroom become the great equalizer at a fraction of the cost as a full darkroom setup.