All of the other RPC mechanisms you discuss suffer from the same problems that I gave for SOAP. And in all of those cases the use of those on servers regularly leads to problems. They don't generally lead to horrible client issues though since the clients at least tend to be relatively solidly designed. (Compare IE with, say, Microsoft Word for security. There is no comparison. IE, for all of its mistakes, had to take it into account from day 1. Microsoft Word, as the routine macro viruses can attest, was not.) There is certainly nothing magic about SOAP that makes it better or worse than them.

But I single out SOAP because it is the protocol of choice for would-be buzzword-compliant people (a group who I have distrust and distaste for at best) who want to enable a wide variety of random clients to use a programatic interface to use over the Internet. It is particularly popular among people who want to do the kinds of things that firewall administrators (rightly) are inclined to audit and possibly block. It is even being marketed that way.

Therefore I believe that the density of scarily moronic things being done with SOAP is much higher than with the other RPC mechanisms that you mention. If people were being encouraged to open sloppily written Excel spreadsheets over the Internet with another RPC mechanism, I would be just as unhappy with it. But it isn't another RPC mechanism, it is SOAP which has that dubious honor, so it is SOAP I am speaking up about.