I don’t think we read the same thing.

> Models can be pulled along other axes, however, such as whether memory locations must be tagged in order to be used in a transaction or not, etc. Haskell requires this tagging (via TVars) so that side-effects are evident in the type system as with any other kind of monad. We quickly settled on unbounded transactions.

Snip

> In hindsight, this was a critical decision that had far-reaching implications. And to be honest, I now frequently doubt that it was the right call. We had our hearts in the right places, and the entire industry was trekking down the same path at the same time (with the notable exception of Haskell)

So basically not that TM isn’t workable, but unbounded TM is likely a fool’s errand but Haskell’s is bounded TM that requires explicit annotation of memory that will participate in atomicity.