I "think" it was just specs-manship...the battle of the specifications...back then "economy" 50's were often f/2....then f/1.8 became relatively common...Minolta had to one-up other manufacturers,so they made f/1.7 lenses. There used to be a wide array of almost-identical 35mm film SLR cameras, with very close-quarter sales competition, with VERY similar models from all the makers, vying for sales. ANY edge in comparing two almost-identical models was a help. Keep in mind, that was ALL pre-internet, and magazine "mail-order" was the way people got the best prices. The mega-stores were all in NYC,and many people from across the USA mail-ordered gear from tiny print adverts in the pages of Pop Photo and Modern Photography magazines. People bought sight-unseen most of the time, so "specs" were actually a sales/perception advantage I think.
Minolta waged a "perception campaign", a battle for mindshare if you will, back in the 1970's in the popular photography magazines...they did one campaign with a series of images shot by a "top commercial photographer", using their cameras and lenses, and the cameras and lenses from leading competing camera companies. The identical subjects looked...pretty close. THere were some differences, but for the most part, people got the idea that...Minolta gear was the same as Nikon, Canon,or Pentax. Or Olympus. Or Konica. At that time, there were a LOT more 'serious camera' manufacturing companies than there are today. And Minolta's brilliant ad campaign proved that...their gear was about the same as that of the other big camera makers.... Oops!
So, well, maybe that wasn't such a great advertising concept...anyway...in these actual comparisons, run as 2-page spreads, Minolta tried to show that their CLC light metering system (???) was better than the metering in other cameras. Yeah, it was decent. So...the f/1.7 lens was a selling point. FUJI for example, had some f/1.6 Fujinons....whoa!!! Big whoop! CLC was "contrast light compensating" system, as I recall.
"Only from the mind of Minolta." That was their slogan during the early autofocus era, when they actually had THE BEST systems on the market...better than Canon, far better than Nikon. But, within a half decade, they lost the plot, bet hugely on APS-C film, a format that was stillborn, and then within a decade, washed out of the film-developing, photo paper,print developing machine, and camera and lens businesses.