1. When the volume of the coin/pair is not really upto the market they expected to be and maintaining wallets and spending funds for the security of funds will be a net loss.
2. When government/regulators force them to do.
OKX is a Korea-based exchange, it does mean the regulation is forcing them to do it, and maybe low volume as well is the issue. people today don't care about privacy which i guess there is not much volume to the pairs and maybe the coins are also not getting many buyers.
i don't even see many people discussing anymore about these coins. there used to be more developers launching anon coins but this year i see none. the market is just saturated.