[Cryptography] What are the privacy implications of bitpay

[jamesd at echeque.com]

With the designed method of bitcoin, you can pay someone quite 
anonymously.  They issue payment address, which is actually a public 
key, and then value mysteriously appears in the blockchain for that 
public key, with no indication of how it got into the blockchain.

Bitpay, however, initiates a direct conversation between the payee and 
the wallet, and it looks to me that entities cosy with the state are 
pushing bitpay onto us, demanding payment by bitpay.

Bitpay initiates a conversation between the website and the wallet, and 
thus, and thus, modulo vpns and all that, locates the physical location 
of the wallet.  But that in itself is pretty harmless, because you have 
to interact with their website anyway, so you already leak that information.

What additional information goes into a bitpay payment?  Seems to me 
that it is being pushed for ulterior and unrevealed reasons.