it failed? today's most popular programming languages are about half smalltalk derivatives (python, js, java, c#, and vb.net, but not c++, c, golang, sql, and fortran), apple is the world's most important computer manufacturer, wimp guis still dominate on computers that have keyboards, every web browser includes an ide with an object inspector, and virtually all programming is done in ides
The royalties on the laser printer alone earned Xerox back PARC's entire expenses 200 times over but PaRc FaIlEd BeCaUsE xErOx DiDn'T kNoW hOw To mOnEtIzE tHeIr InVeNtIoNs.
that doesn't sound like failure to me