Crankcase scavenged 2-strokes retain exhaust products in the cylinder in inverse proportion to throttle opening - EGR at source so to speak. Obviously, this is most acute when idling - when anything less than a richish mixture will see them die. That is due to the effect of high concentrations of exhaust products. The same is more or less true for 4-strokes when at idle a higher proportion of the charge is exhaust products that were not scavenged from the combustion chamber clearance volume.
Fuel atomisation 'ceased to be a concern'.
While some of the fuel may still be in a liquid state during induction and the early stage of compression, heat transferred from the piston crown will complete the atomisation.
No argument - that is what I'm saying.
A common misperception is that an engine at low rpm needs WOT to produce maximum power/torque at that rpm - it doesn't. As an example, take an engine that produces its maximum power at 4500 rpm and is running at 1500 rpm (assume a flat torque curve). The most power that engine can produce at 1500 rpm is one third of its maximum. Therefore, the throttle only needs to be open enough to flow one third of the air it can flow at WOT.
If the intention is to accelerate beyond 1500 rpm then obviously the throttle has to be progressively opened further but for merely maintaining 1500 rpm (eg hill climbing) one third throttle is sufficient. Going to WOT may produce more power/torque - but only because it invokes a pre-programmed strategy eg, richer mixture. The airflow will not increase beyond what the cylinders can ingest at that rpm no matter how open the throttle is.
Low rpm reduces mechanical and fluid friction. It isn't a universal panacea though. Heat loss from the combustion chamber will increase as there is more time for it to do so and, there may be pumping losses if running below the optimum speed for the camshaft. And, as alluded to earlier, if the throttle is opened more than necessary for the required air flow, rich mixture strategies may be invoked.
