Earlier quoted context omitted.
For boutique newsletters in small niches, sure, you can see much higher click-through rates. But if you're New York Times, Walmart, AllRecipes - you're sending a daily email to > 10 million uniques, and your click-through rates will be < 0.1%.
How would you know? Have you seen their data? It’s closer to at least 1% for most ecommerce sites. It’s not just for small niche that newsletter works. It’s often considered the most reliable marketing tool (and cheap!), year after year after year.
Yes, for similar sized brands and types of campaign. I worked for quite some time in email marketing for blue chips.