No one could argue that sending 10 personalized emails with a high conversion rate is bad, but consider that, depending on the pricing model and aspirations, a

No one could argue that sending 10 personalized emails with a high conversion rate is bad, but consider that, depending on the pricing model and aspirations, a business may not be viable unless you can find a way to get customers from mass marketing. If your goal is $100M in revenue (which may or may not be a worthwhile goal, that's a different question) and your price point is $10, that's a lot of personalized emails to write.