Actually most of it is either irrelevant or factually wrong.
Basically most metal will not fall apart due to it's own weight.
It has enough tensile strength to maintain structural integrity for a relatively small size like engines.
What you are talking about is a large structure like a high scrapper with a large stress per square cm.
As for centrifugal force you do not want to add more weight especially at the tip since the force effects weight. Another point is with a smaller engine to gain power it needs to spin faster to gain the same amount of compression compared to a large engine.
Comparing apples with oranges.
Since skin and bone's tensile strength is already near it's potential limit with it's own weight.
Various metal has 10~100 times more strength.
A small solid piece of metal by itself is not going to fall apart, and that's not what I was saying. The problem is when you simply enlarge a small engine without using stronger parts and a proper structural redesign, and you put it under operational load,
the engine will fall apart due to the thermal and physical strain.
The engine is not one solid piece of metal, and the majority of strain it receives does not come from its own static weight, so don't tell me this only apply to things the size of buildings, by focusing on the weight and size of an engine you're comparing the wrong attributes.
If you believe that we can just enlarge an engine without using stronger parts, then you have no idea on how physics work or how a turbine engine work. If you agree we do need stronger parts, than your assumption that
"
a larger engine is a lot easier to develop certain amount of thrust since weight does not gain proportional to size since while you can create a larger cavity for combustion to increase thrust"
is wrong.
It all comes down to the square-cube law. Structural components gain weight proportional to its volume, but only provide increased structural strength proportional to its cross-sectional area. The bigger a machine is, the less "specific strength" (in quote marks because this unit is usually used to describe uniform materials) it will have, it means an enlarged machine tend to need a higher weight to volume ratio (density) in order to satisfy the same structural strength requirements. This is completely opposite of what you've suggested.
Another way to understand the issue is to consider that turbofan engines increase its power proportional to its cross sectional area, but increase weight proportional to its volume (not exactly accurate, but some do simplify it this way). This would be a more direct application of the square-cube law.
It is easier for smaller engines to develop higher TWR. You have to realize that this is not something I invented to trash talk about Japanese engines or whatever. Just go read a book about small turbofan engines, see it for yourself. For example:
read p.18, p.387, etc.
It was proven by people in the business of making small turbine engines. You don't have to agree with my explanation, but it is futile to argue against facts.
