From the article:
A more sensible comparison would be Monero to bitcoin considering that both cryptocurrencies are developed on legitimate cryptography and are actually designed to operate as money.
Gavin Andressen's point with respect to the blocksize limit in Bitcoin is or course correct, but Ethereum does not actually provide the answer here. One can actually compare Ethereum to Bitcoin with an unlimited blocksize combined with fixed fees for a transaction of a given size defined in the protocol. This model does actually allow the blocksize to scale, but this comes at the expense of tying the value of the currency to the value of computing resources. This is like using RAM modules or CPUs as money. The result of this is hyper inflation. One can think of a large number of Ethereum clones filling the need effectively driving down the purchasing power.
Monero does have an adaptive blocksize and the total fees per block, are effectively tied to the emission.
https://bitcointalksearch.org/topic/m.16310999 The crucial difference between Monero and Ethereum is that in the case of Monero it is total fees per block, rather than the fees per transaction of a given size, that are set. This means that as the number of transactions per block increases the fees per transaction fall proportionally in Monero but do not in Ethereum.
While the article does identify Monero "as a more sensible comparison" it does not mention this critical point.
Edit: There are a host of attack vectors possible with a fixed fee model, if the the fees are dominant over the emission. In many of these cases these attacks involve the "out of bound payment" of rebates by the miners.