Bitcoin based blockchains are totally capable of microtransactions today, but only through channels. So you and I could fund a channel between us, and we can shift that balance at any speed we want, not needing to wait for 10 minute confirmations and only needing one transaction on the blockchain when we close the channel.

Lightning Network technology adds to those channels the ability to pay someone you are not in the same channel with but rather the payment hops through other peoples channels.

I think the language used by DAG developers is deceptive also. I mean anyone can validate a transaction intended for a blockchain. What matters is confirmation, not just validation. Something valid now can become invalid later, after confirmation. In a double spend both transactions are technically valid, until one of them is confirmed in the blockchain. And DAGs usually have external and sometimes centralized servers to do actual confirmation (the thing that matters most), and on top of that, it doesn't make sense they are feeless because how are servers doing the confirmation being compensated? In the end they will have to find external means to be compensated, which means they can be corrupted in some way.