This is a controversial post I found in the IOTA slack. The concerns are regarding IOTA's security. How does IOTA approach the specific statements?
IOTA is fundamentally broken.
It's a PoW crypto that uses a dag (ok). Hype aside it's a minor change that's equivalent to transaction chains in Lightning Network or Raiden, offering exactly the same advantages (asynchronous) and disadvantages (lower security). Where iota breaks down is assuming a model with everyone mining their own transactions can work.
What PoW means in practice is that cost spent on mining = security. Ie. $100 fees per hour? Spend >$100 (in energy used for mining) to rewind these transactions. It's better with asics as that adds 'has access to asics'.
The reason PoW currencies currently work is because cost is shared among every owner due to inflation - with it, total cost per tx in bitcoin is $81.91. Iota is economically exactly like Bitcoin without any block reward, which requires every transaction to pay a very high fee (in energy used for mining) for any reasonable security.
Firstly, it requires every iota sender to be able to do that - which means high-speed hardware capable of mining and access to required energy. A premise fundamentally incompatible with light IoT devices.
Secondly, the fee market doesn't work due to the free rider problem. Everyone is going to use low fees (=low PoW expenditure) hoping that a high-fee transaction confirms it, or lots of other low-fee transactions. Which means no high-fee transactions, which means no security at all.
That's why there's a coordinator. It's never going away. The fundamental design is hopelessly broken.
How can I argue against that?