Except there's no relation between the two pictures!. It was posted to show the typical construction behind most Marshall and other major brand instrument tube amps. You have to admit that it's a clean design and quite servicable.
From how clean the chassis picture is, presumably it's a modern amp built using old techniques? - to scam even more money from the customers!.
Scam? Not. I disagree with you there. People pay for the R&D behind the product as well as the reliability factor and probably for the respected name... just like they pay for the hood ornament on a Mercedez or Cadillac when other brands offer similar features/quality for less.
But Marshall are the classic rock/heavy metal amp - many people wouldn't use anything else. Personally I think such amps, and expensive guitars for that matter, are vastly over rated - a good guitarist makes anything sound good, lesser players buy the gear they see their heros using - but that's the way the world works, it's why companies sponser their users!.
While you are partially correct to some degree, often in life you get what you pay for. Better instruments incorporate finer materials, more accuracy, better tolerances, detailed construction, better QC, etc. Or at least they're supposed to as that's what the more famous brands have built their reputations upon. True, that a good musician can make most any quality instrument sound musical. However, the mindset of many budding musicians can be psychologically affected by both poor or good quality equipment.
When I started out in bicycle racing my first bike was a $100+ Gitane from France. It was an entry level racing model that seemed to work for me at the time. As I progressed and became better at the sport, my taste and need for better bikes escalated to the multi-thousand dollar models. I reached the peak point of my physical abilities and from there on the quality of the machine could give me another edge... hence the reason for expensive bikes. On the otherhand, my guitar skills are just average for an amateur and as much as I would love to drop a few thousand dollars on a LesPaul, I see it as an impractical use of money just to "look good". My '63 Strat was purchased many, many years ago for a mere $125 and it has gained a huge value over the years to nearly 50-75 times that amount. So in my case I can boast that I own a multi-thousand dollar guitar while only investing a mere $125 for it! So, now I look good, feel good, and sound fair!