There's a "why" link on the upper right-hand side, but even if you click on it, you'll see they don't really make a compelling case to distrust google. Because they scanned books and digitized them?
They don't say Chrome itself is bad, and therefore do not seek to explain it. The page is less a technical break down and more a call to action ala activism. Chrome itself isn't an issue, it's one of many tentacles, and one of the bigger ones, leading back to Google.
> If you're arguing for something you need the full argument.
No you don't. In fact, for many rhetorically primed things, such as opposition to Google, and especially in the realm of activism, explaining over and over why you're doing a thing is often not done because it's not necessary.
Every environmental protest doesn't need to include explanations of the Exxon Valdez and BP's Deepwater Horizon. Once things reach a certain level of cultural "it is known" explaining over and over is not required. If you're attending a protest, you know about these things. If you don't, others at the protest will tell you. If you do and aren't convinced, they aren't interested in reaching you.
Even the WHY page is bad. It only states that "google is bad" "they are not your friends". Okay, proof, cases, overwhelming evidence that would force people to stop?