I decided to crunch some numbers because I was curious about your claims. Here is what I came up with:
Suppose 10,000 players per server with 5 layers with 2,000 players per layer.
Now the tricky part because we can't actually know what rate players will reach 60 so I am going to use the wow classic survey results. I know this is flawed because it only takes into account people who took the survey but it did have 40,000 responses which is greater than the 10000 on our server so it is possible to think of a theoretical scenario where 10,000 of these respondents ended up on the same server so the statistics from the survey hold.
Moving on...
According to the census 11.9% claimed 60 in 1-2 weeks and 23.1% claimed 60 in the first 2-4 weeks. This account for 35% of our player base reaching 60 in the first 4 weeks.
Part 1 (weeks 1-2):
11.9% of players reach level 60 by week 2 and begin farming the layers. This is 1190 players. Since there are 2000 players per layer it is highly unlikely all players could be on the same layer but lets suppose they do in order to calculate our upper bound on farming. Keep in mind these farming numbers are assuming that all 1190 level 60s fit into one layer and have perfect layer hopping with nearly perfect timing as for each layer to have equal amounts of nodes available. This means each of those 1190 players could effectively farm 5x as many mats.
Part 2 (week 3):
The amount of 60s is effectively the initial 11.9% of players plus half of the total 23.1% census's week 3-4 levelers. This is 11.9% + (23.1%/2) = 23.45% which is nearly double the initial amount at 2 weeks. This means that now those 60s can farm at most 2.5x as much mats (half of the initial 5x amount).
Part 3 (week 4):
At this stage 35% of characters are 60 meaning that 3500 players are level 60. They cannot fit all on one layer, similar to our 1190 per layer example above lets say 1000 60s per layer meaning that 3.5 layers are farmed out at a given time, so we have this situations:
Layer 1: 1000 60s farming
Layer 2: 1000 60s farming
Layer 3: 1000 60s farming
Layer 4: 500 60s farming
Layer 5: open
chances are by the time one layer with 1000 players farming finish the 500 players on another layer will likely have finished. That leaves one open layer that 1000 players will compete for meaning 1000 players are getting 2x the amount of resources. This will continue for a little longer until eventually there are 5000 60s in which case 1000 60s will exist per layer and the high level farming areas will be saturated. This (again, according to census numbers) will happen at week 6.
So in total, with only farming and perfect layer hopping and perfect node timing:
For 1 week (week 2-3): 11.9% of players will gain 5x the amount of resources that they would normally farm.
For an addition week (week 3-4): 23.1% of players will be able to farm 2.5x the normal amount of resources that they would farm.
For 2 weeks (week 4-6): 10% of players will farm 2x the amount of resources that they would normally farm.
The net resources in the economy that otherwise would not exist without layering is not enough to break the economy in this instance. If the farmers sit on their mats (removing themselves from participating in the economy for the particular resources they farmed) demand goes down but only until they use all of their resources (they don't have enough resources to last until phase 6 as your "permanently affect" claim implies). If they decide to sell/corner a market they will only have a small amount of potential buyers as very few 60s will be purchasing those items immediately. As more players reach 60 the initial gouging will pass until those 5x/2.5x/2x excess mats are sold and then the market will reach an equilibrium long before phase 6 (again, as your "permanently affect" claim implies). I would love to hear your well-formed and mathematically backed arguments but judging from your responses in this thread you have not provided any sort of rigorous arguments involving math or economics.