Why Exchanges Won't Publish Cold Wallet Address to Prove Solvency

[Colorblind]

I wonder Why it is that only fraction of exchanges openly publish their CW address as a proof of solvency (like Bitfinex does https://bitinfocharts.com/bitcoin/address/3D2oetdNuZUqQHPJmcMDDHYoqkyNVsFk9r)?

Isn't it fairly easy to track Cold Wallets of a big exchange (like Bittrex) to peak if they are solvent?
Why on earth it is not a common requirement for every single regulated (and non-regulated) exchange? Or am I missing something here?

[OmegaStarScream]

Bitcoin itself is transparent because all transactions are recorded in the blockchain so even If an exchange decide to not share the address with people, users could eventually find it with some research because the different transactions will lead to it, the funds can't simply pop up there.