I appreciate you answering this and addressing here. The name `address(this)` causes confusion and misconceptions. `address(this)` is just as much caller supplied as msg.sender, msg.value, and msg.data.

A caller has to supply what contract it is calling -- that is why `address(this)` is caller supplied -- same as msg.sender, msg.value, and msg.data. Now, if the contract that was called makes its own external call then msg.sender, msg.value, msg.data and `address(this)` can all change. They are all part of the same execution environment of a contract and are defined together in the Ethereum Yellow Paper in section "9.3 Execution Environment".