An interesting mix of opinions, reflecting experience and knowledge of photography in the main.
The often blind partisanship towards zooms really conceals a big issue with them. Very few are made for advanced users. Zooms fall into two major categories, each either side of the niche most a7x users occupy. They are either pro tools or low-mid consumer items made down to a price.
None will excel at what photographers want in travel photography - the creation and capture of unique imagery, a familiar subject seen with fresh perspective perhaps. Zooms are total compromises, as we see them today. Too slow, too heavy, too large, too 'look over here, a tourist'. Zooms are what phone users use when they think they mean business. Zooms put distance between the subject and the shooter. Before long, the shooter feels he is 'harvesting' images.
They disrupt the creative process by encouraging the erroneous message that they can take all the photographs that appear in front of you. Sensory overload and random shooting is the result, you no longer think through what kinds of images you are shooting for, you have just surrendered large DOF control and very few mid zooms are decent below f4 in any case. Even the lens hood is a compromise as it is designed for the widest FL. Zooms are a kind of tourist visual shorthand. Zooms turn your camera into a point and shoot.
Prime lenses of the caliber mentioned by the OP are very different in usage and results. Where AF f2.8 zooms are designed to deliver strong central performance wide open to f4, and peak at f5.6, primes like these are far broader capability lenses. They are truly excellent wide open, rise to best in class IQ in middle apertures, before remaining so strong at f8, right across the frame.
They are designed for great color and bokeh control, on a level no zoom can match. Zooms are loaded with fancy glass which has the side effect of producing horrible bokeh artifacts.
Zooms are inconsistent - what you get at 24mm is not what you see at 70mm. The performance profile is very different in key ways that you cannot calculate in shooting. What if you want great corners at 25mm at f4? What if you want the 85mm FL for portraits?
What if you value intimacy and a close connection with your subjects? A small camera - so obviously built for use with small-moderate lenses - is essentially a small request for a photo. A large camera/lens or even a small camera/large lens is a very different level of request. Your gear now closely resembles what everybody sees on the nightly news, swarms of mad guys working with DSLRs/zooms, trying to get a shot of Obama/Pope/significant other celeb.
The result is wooden expressions on tentative faces. No spontaneity.
You can raise an a7 body and any of these primes to your eye in an instant (total shot ready carry 900-1050 grams), and can maneuver it very fast even using just the right hand. Much harder with a 900-1000 gram zoom tugging at the front of the camera, now a 1500 gram beast.
I see the zoom guys quite often, when out and about. They often have two cameras, one with a 24-70 the other a 70-200. Gotta be prepared, right? They look like paramilitary or surveillance, and people avoid them. They bang into everything because their stuff won't fit inside a bag, and people see them coming from a hundred meters off. So the paradox is that while promising versatility zooms deliver severe restrictions on most of what we value as enthusiasts.
