Well, for me it’s important as I save important info in it, technical or related to specific conditions or even what was there to see.I wouldn't say standards had been cut on your friend’s training, as you describe a competent diver. I’ve had students complain that they hadn’t received certain aspects of the syllabus, either from me or another instructor. Its quite amusing when the bit they complain about it the instructor’s pet aspect of training. For me its planning the dive and diving the plan with proper gas management.
It’s down to each individual how they maintain a log; be it a book, separate sheets of paper, electronically on Word, Excel or an app, or even just rely on your computer’s memory.
As they’ve been diving with you, when they’ve seen logbook completion; from you.
Bear in mind a logbook can be fabricated, so reliance on one for experience can be misguided. Hence the importance of operator’s check out dives.
What he also missed are other very important things like what to do in an emergency, how to clean a mask and others that maybe we have not even discovered. He now does what we saw together in Egypt and our AOW instructor pointed out.