The thing about this is your talking about paths to two different results.
On the one hand you have the traditional range of reps and sets. Let's say I do 3x8 squats or for this example weighted push ups. When I put so much weight on my back that I can only barely do 3x8 I'm pushing my muscles to their limits and inducing hypertrophy. This leads to more muscle mass and maybe next week I can go up a few pounds. I'll probably be able to do 3x10 or 3x12 later on, (a lot of programs are based on this) but I won't hit 100 push ups only doing 30 or so at a time.
Contrast this with low weight or body weight and extremely high reps. The limiting factors on how many unweighted push ups in a row I can do are different, for example when's the last time lactic acid build up stopped you from hitting a PR? This type of muscle failure is not nearly as productive at inducing hypertrophy, so as a result you gain less muscle mass and strength. You'd also see little difference in how much weight you could have on your back and still do push ups.
All that being said, you don't train for a marathon only doing parachute sprints. You'll see a lot of "first responder" regiments that have workouts like you've described, the idea being they need extended periods of strength. Depending on your goals you may find either approach attractive, but I'd say 95% of people that working out for strength/health/looks would be happiest with typical strength training program and some good cardio (I like rowing machines because they're amazing cardio and still make my muscles feel like they're being engaged.) Another advantage is time, there's no reason an average person should have to spend more than 3-12 hours a week to accomplish reasonable goals.