You have Tencent but you also have a lot of utter dross that deserves to trade at low multiples because they don't earn good returns, the balance sheets are poor or they are simply run for the benefits of the CCP first, employees second, customers third and minorities not at all.
Compare to the US where you have scores of strong companies, professionally run and much better disclosure and protection of minorities. There is also a strong argument that companies with stable earnings should trade at higher multiples than cyclical businesses for many reasons - the US has far more food, pharma and consumer companies than China/HK
Anyway, simple PER comparisons neglect balance sheets( levered companies should be cheaper than unlevered companies) , consistency of returns (volatile RoE's should be cheaper than stable RoEs), capital allocation ability (companies that can profitability invest cash should be more expensive than those who can't), cash conversion (companies who generate cash in excess of accounting earnings should be more expensive than those that don't), growth runway (companies with plenty of growth ahead should trade on a higher multiple than those who have peaked out) etc etc. Many factors to consider, not just aggregate PER.