Whether it is popular on SB or not, IMHO the most popular beginning certification courses with customers are the cheapest courses. Here in Hawaii, and in many other similar locations from what I've seen, heard and read, the cheapest courses are typically 3-day courses. Many of the 3-day courses will spend 10-ish hours the first day; morning Academics, afternoon Confined Water.
This is not only the predominant class that tourists sign up for. AFAIS, locals also mostly go this route; 3 Sundays, 3 Saturdays, Sat-Sun-Sat or a Holiday 3-day weekend. The last option is tougher in places like Maui where many Beach Parks are off limits to commercial operators on Holidays.
There are more than one agency that this can be done through, but the details here are what I have seen shops/resorts/independents do for PADI OW. This has been going on for at least a decade, probably a couple, so e-learning really has nothing to do with it.
Students with good snorkeling experience, good physical shape and endurance, who have completely read the book, watched the DVD and completed as much of the Knowledge Reviews as they can (book/DVD/KR's takes ~8 hours IMHO) BEFORE showing up for the first day of class will probably do all right in this format, as long as the student instructor ratio does not exceed 4-1.
With regards to the post above; if 8-10 students are completing the Academic portion with one instructor in 1.5 - 2 hours, that is not enough time, and that is pretty much not an opinion. There are 4 quizzes, with each one being graded and discussed followed by a 50 question final that also gets graded and discussed, which is at least 2 hours for that many students. Pretty much means going over the KR's is not done to complete the Academics in 2 hours.
IMHO, this is how more than half the divers in the world are certified every year, so if you have ever done charter dives on a vacation many of the divers you have at least been on the boat with were certified this way.