I disagree with your first sentence in its sweeping overgeneralization. The second sentence seems somewhat true but there's a reason why eBay failed in China: they ported their English website over without consideration for the idiosyncrasies if the chinese market and netizen.
These two sentence are also not intrinsically linked. Just because there has been protectionism does not mean that the China apps are automatically worse. In fact, a bunch of features of weibo and we chat have found their way to Twitter and WhatsApp. (One example are voice messages which were a core part of wechat from the start. They were important to get people in rural areas or older people to use the app, due to the difficulties of typing Mandarin, especially dialects.)
Voice messages have been around since before smartphones, come on.
There is little reason to expect companies that have had multi-national success not to succeed in China if it weren't for protectionism; while there are certainly examples of poor execution, you'd have to be blind to think that was the reason for every such case, or even a significant portion thereof.
That's not entirely true. WeChat in many ways is more impressive than whatever US equivalent is for a Chinese audience. And Didi executed far better than Uber without protectionism being in play. It's nontrivial to execute in a foreign culture to your own.
Indeed, Chinese apps have diverged significantly from what's used in the West. There were a bunch of Chinese copycat apps at first, but some of them have been supplanted by new and very different apps. Everyone in China used to be on a Facebook copycat called "Ren Ren," but it's gone the way of MySpace, and everyone is now on WeChat, which has no equivalent in the West.
These two sentence are also not intrinsically linked. Just because there has been protectionism does not mean that the China apps are automatically worse. In fact, a bunch of features of weibo and we chat have found their way to Twitter and WhatsApp. (One example are voice messages which were a core part of wechat from the start. They were important to get people in rural areas or older people to use the app, due to the difficulties of typing Mandarin, especially dialects.)