That's a tip that was valid before internet pricing became a thing. Essentially, the price you see online is the price you pay now, because dealers have (mostly, and FINALLY) learned that if I don't see it at a good price, I'm not interested. Some still have the 'come in to see the price' and they don't move the volume of those with robust internet sales teams [source here that i don't have. Anyone have one?]

Now the extra costs come in on accessories, service plans, and warranties, whereas they used to make more profit on the actual sales.

We just bought a vehicle in March, and it was the best, least friction experience buying a car. I found the package I wanted, I found the color I wanted, I evaluated the price against online sources such as KBB, truecar, and those types of things, then I contacted the dealer who had it in stock online and set a date to come buy it. They didn't try any weird old-timey car sales tactics, because the price is the price. They offered extras, add-ons, the warranties, and service packages, with clear prices, and were respectful when I declined.