Many times, the designers will write far more extensive instructions than what you see, but the editors, often non-knitters, edit for space and photo constraints. So they sacrifice comprehension for pretty pictures, essentially. It’s a constant source of frustration to knitting designers.
I have to admit, with all due respect, that many times, it doesn’t make sense to simply “Trust the pattern”. Knitting patterns are rife with mistakes, omissions and poor editing. Errata should be checked and double checked, and if you’re going nuts with a poor pattern, consider that perhaps it’s not you, it’s the PATTERN!
The Yarn Harlot has suggested that because knitting designs are primarily aimed at women, they are far more forgiving of mistakes and sloppy proofreading than men would ever be. As proof, she cites the very low number of errors traditionally found in men’s woodworking and craft magazines. They know that if they hand a guy a piece-of-garbage set of instructions, he’ll simply refuse to buy the magazine again, and they’ve lost his business. Not so women. We’ll keep going back, thinking it’s simply US.
It’s a fascinating viewpoint, actually. It reminds me of when men were targeted for Rogaine hair cream back in the 90’s. They tried it and complained it was too drippy, too fussy, too much work, and refused to buy it anymore. Rather than change the product, Rogaine changed the focus of their advertising - to WOMEN! They knew that despite the inconveniences, women would deal with the product. Interesting, no?