Even today, the best zooms aren't quite the optical equal of the best primes if you look at something like the data at DxOMark. The differences in actual results are a lot less noticeable, though, and complaining about it amounts to picking fly poop out of pepper, especially in a world where most photos are viewed on fairly small screens, not printed at 24x36 inches to hang on a wall.
Suffice it to say that working pros have been using zooms for a long time. They have their place, especially if you don't know what kind of shooting you're going to be doing.
Primes tend to be more compact, although they're losing that advantage with manufacturers producing ginormous fast-aperture lenses for their new mirrorless rigs. Look at the 50mm f/1.2 prime for the new Nikon Z mirrorless. That thing's six inches long and more than three-and-a-half inches in diameter. That's a monster lens.
The Z-mount f/1.2 50mm lens weighs thirty-eight ounces...as much as a Colt 1911! I'm sure it gives stellar results, but the quarter-century old 50mm f/1.4 AF-D does, too. While the new Z 50mm is bigger than a beer can, the old AF-D is the size of a snuff can; it weighs eight ounces instead of two and a half pounds; it's three hundred bucks and change as opposed to more than two grand. If you're talking about the old lens, yeah, there's a big size and weight savings by going with a prime instead of a zoom. With the newer one? Not so much.
I've got a couple of nice, fast normal primes for my APS-C sensor mirrorless cameras, the Sigma 30mm f/1.4 for the Sony E-mount and the Zeiss Touit 32mm f/1.8 for the Fuji X-mount, and sizewise they're about the same as a nice, compact, travel zoom on either camera.
Especially when designed specifically for a crop sensor, they're not obtrusively large, and I like the flexibility.
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