You can say the same about Facebook and Google in China...You can sideload or use VPN. Some do. Most don't. Blocking FB & Google ecosystems allowed for China to grow their own competitors.
China has invested into its Great Firewall, which is far, far better than the techniques most ISPs here use to block websites. Besides, VPNs aren't banned, and the government isn't cracking down on generic VPNs. It's far easier to get a VPN in India to browse TikTok than it is to get a VPN in China to browse Facebook. You can even see it in the list of apps that were banned - there's two literally called "VPN for TikTok".
The thing is, there's hardly anything outside GFW that an average Chinese would want, local alternatives often are feature rich and considered "more advanced", outside news are dismissed as "obscenely fake and hostile".
In the few Chinese that do pay for VPNs, most women use it to access Instagram for celebrities, most men for porn on Twitter.
Exactly. People are missing the point that bringing in new customers is a lot harder if you have to go through a number of additional loops to install an app and even find out about it. Local rivals have a massive leg up. Over time, once local rivals develop and they are easily accessible and feature rich, then people will stop using the Chinese apps. Just look at the latest YC batch which was full of Indian startups.
Facebook Messenger also "wasn't even started till 2011". Before 2011 China had very mature local messaging (QQ, from the company behind WeChat) and less mature but burgeoning social networking (loads of them I believe, including part of QQ). Cherry-picking the date of one next-gen product that later took over is meaningless.
Hmm...per Wikipedia the original Facebook chat was started in 2008. Facebook Messenger for mobile was 2011. QQ didn't have their mobile version till 2013.
Facebook cannibalized social networks in the US and homegrown networks abroad. Though we'd never know, I'd believe they would have done the same in China.