1. Well, you are making the extrondary claim that it's super popular here, and in China, but I really don't see any stats to back that up. Instead, I am looking at the ratings (which is an indication of popularity, in my opinion) and it doesn't look too popular. Looks like the show has always struggled with their ratings. And again, if ABC is aware that AoS is so popular (online, here in the US, and in China) then why were they willing to cancel it at the end of Season 4? I do realize that entertainment is a business and canceling the show probably had to do with the fact that it wasn't really making money (which in my opinion a super popular TV show would make money and TV networks are willing to invest in. For example, HBO literally gave the showrunners of GoT a blank check to make as many episodes as they wanted to but refused to go past 6 episodes and 8 seasons- and that is, in my opinion, another story).
2. Again, in my opinion, the longevity of the show is due to Dinsey forcing ABC to renew the show for a 5th Season. Not because it's was popular but (many) on the speculation that they want to use the show as an MCU preview night type of show. Some TV shows that I assume are the best ever only have a limited number of episodes. Star Trek the Orginal Series had only 3 or 4 seasons. Breaking Bad only had 6 seasons, Firefly only has 1 season and one feature-length movie (which I do own), Farscape only has 4 seasons and one 2-hour TV movie, Eureka only had 5 seasons, The Expanse only has 3 seasons before SyFy canceled it and it was saved by Amazon, The Tick on Amazon only has 2 seasons, GoT only has 8 seasons and like 70+ episodes (again, the last season was utterly terrible but the good seasons was when GRRM was still writing episodes back in Season 4), etc...
3. It looks like we are not going to agree on anything and sure YMMV but I feel like we should just end this here.