Well, this went sideways quickly.
It is probably a cultural thing, but in my experience on toy train forums, we tend to do a lot of sharing and expression of good will. When we see that a person appears to have misunderstood something, or is going down what we know to be the wrong path, certainly a poor choice by way of engineering and physics, we jump in and caution the person. I think this is what was being offered here: expressions of good will, some cautions, and suggestions for another way of achieving what was understood to be an aim or a goal.
Power supplies are rated for a maximum output. They may only ever need half their rated output, but they are designed for more....but a defined safe upper limit. What happens on the rails is the variable that determines how much throughput, or usable amperage, the power supply will provide at any given moment. If it is a single small sound-equipped diesel pulling six box cars and a caboose on level track, it will be somewhere between 0.3 and 0.7 amps, depending on the ease of rolling of the cars and the efficiency of the drive. We were talking of a much larger number at one point, all working concurrently, and that figure was 1000. Taking the lower number of amps above, it still comes to 300 amps needed for pulling the trains behind the 1000 locomotives. My question would be as follows: will a 120 volt power supply with a DC conversion and output of 3 amps provide 100 times that amperage for more than about 10 seconds before it made a lot of smoke? Umm....no.
Secondly, at what outlet in a standard coded home would one expect to be able to draw 300 amps? Nowhere, not even boosted at the 240 volt circuits to the hot water heater and the kitchen stove.
