Be careful of assuming you know what other people's experience is! To give you some context, I ride between 5-6,000 miles per year on non-electric bikes - a mixture of high speed London commuting and tours, in the UK and Europe. My main bike, and its components, have a fairly demanding life. I assure you that the fact that other people may use their bikes less and/or be older than you or than me, doesn't make me in the slightest confused!
As you say - and I agree wth you here - some components are rubbish and drop to bits before you try to use them. But Powabyke don't fit those - they fit mostly low end Shimano kit, which is not necessarily the slickest to use but it is generally reliable. Remember Powabyke is the market leader with a reputation for reliability. Their bikes are not necessarily the best performers but they do keep going (ask any bike shop).
I know from my own experience, and reading that of others who have more than me, that all bike components wear out (apart from quality steel frames, if looked after). High end components are more expensive, not because they last longer. They are typically smoother to use, and lighter. Neither of those things make them longer lasting and in many cases make them wear out quicker, because they simply use less metal to save weight, they are more delicate, or use aluminium rather than steel.
Regarding your old fashioned point, get an old book, look on eBay, or take a walk around an area with lots of old bikes parked. There are loads of 20-30 year old bikes in daily use, as they last a long time. They look nothing like an Ezee Sprint or a Powabyke!