100% agreed to all you have said, however, I would like to say following:
I logically and personally think that thin oil grades (like 0w-20, etc.) have little-to-No to do with bad fuel quality, climate conditions and pollution. Their main purpose is lubrication and heat dissipation of the moving parts of engine, and Pollution & fuel do not make direct contact with engine oil. Oil Grade / Viscosity is more based on engines' oil pump, clearances, etc. If one is going to pour thick / not-recommended oil grade (like 10w-40, 20w-50, etc.) in an engine which is designed for light and thin oils (like 0w-16, 0w-20 or 5w-30 Max. like in case of Toyota Aqua), I think the engine will get destroyed quite early.
If Atlas Honda is pouring 0w-20 in Civic, BRV, etc. they are well aware of pollution, bad fuel quality and high temperatures here, and while taking approval of 0w-20 for use in Honda vehicles in Pakistan, they will have definitely addressed these issues and concerns to Honda Motors Japan. If Honda Japan has approved 0w-20, it means everything is OK and all concerns have been taken into account. Otherwise, they know, many warranty claims regarding premature engine failure will be there (due to incompatible oil, etc.) and they cannot afford it.
Regarding pollution and fuel quality, I think Japan and USA can be compared (I am assuming less pollution and excellent fuel quality in both countries, as compared to Pakistan). Still, Toyota Japan suggests 0w-20 and 5w-30 in Hybrid Vitz, however, Toyota USA only suggests 5w-30 in Hybrid Yaris. If Japan has cold regions, USA also has regions as cold as Alaska. So, if Toyota USA is suggesting only 5w-30 to be used in Hybrid Vitz, even in Alaska; the differences are clearly there. And the list goes ON...
If I have to choose between 0w-20 or 5w-30 for an abc vehicle (both are OEM recommended oil grades, and are only 02 grades recommended by the manufacturer), only air temperature will be the deciding factor for me; neither pollution nor bad fuel quality.
To cater for air pollution, one can just keep air filter in top notch condition, along with OEM recommended oil change after regular intervals. Air filter are the lungs for engine. If its always kept clean, engine is going nowhere. To cater for bad fuel quality, one can just keep fuel pump, fuel filter, fuel injectors, catalytic converter clean and healthy.
Secondly, I do not know about Honda Motors Japan, however, in Pakistan, Atlas Honda Limited does not make oils itself. I have learned that Honda 0w-20 and 5w-30, API SN, Fully Synthetic engine oils are the same as Total Quartz 9000 Future Series 0w-20 and 5w-30. Just difference in branding, packaging and packing.
Still, I respect your opinion Sir, and will not not drag the debate any further (or may be, agree to disagree? )