With 10MB blocks, costs of running a node would increase exponentially.
Unfortunately, this is simply not true. Another statement without proof.
You can’t bend the Laws of Physics. Block propagation slows down as block size grows.
We are discussing raising the block to 10mb here. For this case, there is no problem with the distribution of blocks over the network at the current Internet speed. You do not take into account the growth of Internet speed, as well as the development of technology. I understand you don't know about the Compact block technology.
You were zombified 4 years ago, since then you have not turned on your brain. What is pushed into your head, then repeat.

Would we really be able to apply "meters" to decentralization?
For a given payment system: there are middlemen present, or they are not.
It's a binary phenomenon...
However, users of bitcoin forums constantly use expressions such as"decrease/increase centralization/decentralization". Even bitcoin developers don't hesitate to use these expressions. Although they must have an engineering mindset. And it's amazing. How can you claim a decrease/increase in some indicator if you do not know how to measure this indicator, if you have not determined how to measure it? This is nonsense.