- I am not convinced that a tangle is stable/convergent/secure in all circumstances. Even if it seems to work under all tests so far, it may well fall apart under a clever but not-too-difficult attack, or perhaps even just on its own.

Possibly due to the IOTA devs sharing similar concerns, IOTA's software currently relies on centralized checkpointing.

IOTA and its research proposal predecessor DagCoin don’t record any form of objective transaction finality (such as Byteball’s stability points) for the unsynchronized partial orders of transactions in the ledger!

Transactions include some PoW so that tips (leaves) of the DAG branches are extended with probabilistically more cumulative PoW as new descendant transactions are issued, but there is nothing forcing these unsynchronized partial orders to converge on a single-total ordering, i.e. there is no probabilistic finality of transaction confirmation. In fact, (in the absence of IOTA’s “Coordinator” centralized servers) the partial orders will have conflicting orders due to double-spends, and there is no leadership election process nor witnesses set to decide on the ordering of the conflicts.

The (load of misleading technobabble bullshit) theory of their convergence to a single total ordering based on network propagation order (which experts know can never be provably consistent for all nodes without some synchronization algorithm) and/or a model requiring centralized enforcement of the algorithms employed by the payer and payee, which is inherently insecure due to unconstrained divergence. IOTA employs centralized servers named “Coordinator” (apparently not mentioned at least in the early revisions in the whitepaper) to enforce the whitepaper’s Monte Carlo strategy on all participants. IOTA has been challenged numerous times by numerous people (including the guy who challenged the developer @Come-from-Beyond to remove their Coordinator centralized enforcement in order to prove that IOTA will function decentralized, and afaik they have never done so.

That guy was threatened with a lawsuit by the “IOTA Founder” @iotatoken (real name is David Sønstebø) if he would attempt to publish these truths.