To achieve asic resistance, why not switch between a large pool of different algorithms sequentially, with their order and various parameters determined by the hash of the previous block?
Having a pool of different algorithms might improve the difficulty but it will also make it tricky to audit all algorithms for vulnerabilities. On top of that an ASIC might not have to implement all algorithms, they could idle and only spring into action when an algorithm they implement is selected for instance.
The main point of the article stands, no matter how complicated you make your algorithm a special-purpose solution will always be more efficient than a general-purpose one, it's just a matter of balancing the cost of developing the ASIC vs. the expected return.
If, as the article points out, developing chips for minor cryptocurrencies using ASIC-resistant PoW is cost-effective I can't imagine how anybody could hope to design as ASIC-resistant cryptocurrency designed to become the currency of the future. Think about it, in the unlikely scenario where a PoW cryptocoin eventually replaces the dollar the mining rewards will quickly amount to billions of dollars. The incentive to get an edge, no matter how small, would be tremendous.
An alternative scheme would be to change the change the PoW algorithm regularly like the article says Monero is doing, but then you give a huge amount of power to the people selecting the next PoW. Consider how incredibly tempting it would be to develop an ASIC for some PoW algorithm and then have it selected by Monero, you'd have a huge head start.
For mining chip manufacturers the gamble of choosing a few algorithms to support, especially if constraints are promised at the start of the PoW launch, can have favorable odds. There’s only so many PoW algorithms from which to choose.
If something designed to be hard can be made easy, you lose whatever goal you wanted to achieve by the former.
Additionally, imagine you bought GPUs. Then of course you are going to oppose to changes destroying the profitability of your GPUs. If you then read about someone writing about ASICs fostering centralisation, you'll be inclined to approve such statements.
However ironically it has been shown that quite possibly GPU mining is more prone to centralisation attacks than ASIC mining.
When it comes to ASICs, it's very difficult for you or me to buy them outside the US or China. Someone wanting to set up a mining farm with 500 of them can probably arrange something, but if I want to buy just one here in Iceland, I'm screwed. No one ships single ASICs to Iceland for a sane shipping fee. Most won't ship them outside the US at all.
As a result, almost all the hashpower in bitcoin is coming from the US or China, and from the rest of the worlds perspective that's not good. It is /definitely/ within the Chinese governments power to seize all of bitmains strategic reserve of chips and use them to perform a 51% attack on bitcoin.
The benefit of ASIC resistance is that it forces everyone down to graphics cards or at least FPGA boards, and both of those can be bought over the counter in any western country, so it spreads the hashing out geographically, which is desirable from a resilience standpoint. If ASICs were widely available it would be a different matter, but since they aren't, it's overall better to force them out of the game for now.