Why is not Lisp more widespread? If it is really that powerful, people should be using it all over,
If you believe that languages are chosen for their technical merits, you are in for a soul-crushing disappointment.
Such decisions are made based on Strippers And SteaksStrippers And Steaks. Microsoft can afford them. Oracle can. Sun spent so much money hyping Java that they went bankrupt. Twice. A decentralized, heterogenous, volunteer community cannot compete with that.
but instead it is nearly impossible to find, say, Lisp job advertisements.
Funnily enough, the Lisp companies say exactly the opposite: they constantly have job openings but can't find enough people to fill them. (The same applies to Haskell, ML, O'Caml, Forth, Smalltalk, ...)