big fat “it depends”.
Standard software packages? oh they can have a huge risk of failure too. I now lot’s of examples from Outlook and Facebook of “COTS” with bad quality. I could easily imagine small calculation erros in excel having a big business impact. Too many business rely on Excel…
All the teams running CI and CD and Devops – they don’t do user acceptance test, but take the problems that UAT addresses and builds it in early using 3 amigos, MVP and small experiments that can be easily rolled back. Some would say that UAT is a element of waterfall v-model slowly dying out.
But it has it’s uses in large enterprises and public solutions with a large user base requireing traing in the it systems that suports their business processes. I see the business ppl doing this – not the testers. (more here: https://jlottosen.wordpress.com/2017/05/30/the-domain-expert-is-the-tester/)