This article on xml.com states...
The discussion... will help readers recognize the need to coordinate a sequence of SOAP requests and responses, so that the total process looks like a business transaction.
(My underlining of the word "need".)
So whose needs are being represented here? Who actually needs this capability?
A bad habit we have is to avoid questioning the underlying assumptions that we build our concepts on. Distributed transaction protocols are not a "need". They are a means to an end. Why are we trying to recreate them in SOAP?
An alternative is compensating transactions which are also part of a proposed SOAP extension. This is a more practical alternative.
The question then becomes why do compensating transactions need to be part of a wire protocol? Whose design will fit my needs? How do you know?
Separation of concerns should be a key architectural principle. Can we keep the eager standards committees at bay long enough for clear evaluations?