I agree with most of the points here, although I've never seen anyone seriously attempt regression on residuals (instead of multiple regression) outside of an introductory regression course. (Actually, I graded a homework problem on it just last week.)
With all the data collected by tech companies these days, I'd be worried about other problems. It's easy to dig through loads of variables looking for correlations, and you'll inevitably find false positives. If you dig deep enough in your data, looking for differences in conversion rates between Southeast Asian Chrome users and Nordic users of Opera Mini, then you'll also have poor statistical power and end up with wildly exaggerated results.
With all the data collected by tech companies these days, I'd be worried about other problems. It's easy to dig through loads of variables looking for correlations, and you'll inevitably find false positives. If you dig deep enough in your data, looking for differences in conversion rates between Southeast Asian Chrome users and Nordic users of Opera Mini, then you'll also have poor statistical power and end up with wildly exaggerated results.
(I am slightly biased here because I have written an entire book on the subject: http://www.statisticsdonewrong.com/)