IOTA is vaporware and gives all blockchain projects a bad reputation by association. You are right on your points and forget that they rolled their own elliptic curve so you cant use a wallet twice.
Elliptic curves are a type of cryptography and directed acyclic graphs are a type of graph. They have nothing to do with each other at all.
Also all crytpo currencies are essentially DAGs that are synchronized by the ordering of the transactions by whoever mines the block. IOTA pretends that there is something different when the real difference is that they can't decentralize how to synchronize transactions.
The point was that you didn't know the difference between where elliptic curve cryptography would be used and a directed acyclic graph. Also a ledger is by its nature a directed (one direction) acyclic (no cycles) graph of dependencies, it just depends how you visualize it. Just like instructions on a computer are in a sequence, they can be separated into graphs of dependencies which may be woven together.
Other crypto currencies are able to synchronize in a decentralized way with different miners mining each block. As far as I know IOTA's structure makes this impossible, even though when they created it everyone else had already done it.
elliptic curve is a type signing algorithm (like blake2b or sha). if you dont understand what an EC is i dont think you also understand why rolling your own would be a bad idea. the wallet/account seed (your post is semantics in my opinion, whichever seed it is you can only use once, which is a flaw) is directly related again to this issue.
And then they changed it....and no you create a iota seed just like that:
cat /dev/urandom |tr -dc A-Z9|head -c${1:-81}
And talking about scam....ethereum-classic? Bitcoin-cash?
Your talking about a flaw when you just can use a receiving seed once?
Please just read the DAG article, and understand what winternitz-ots means hint (one time signing)
EDIT: In other words every seed could just be used for one transaction...but that has nothing todo with your wallet-seed
EDIT2: And its not a elliptic-curve but a direct acyclic graph
https://en.wikipedia.org/wiki/Directed_acyclic_graph