It was David Travis who hit the nail on the head as to why UX practitioners find themselves being asked for portfolios (my emphasis):
Portfolios are common in visual arts, like design and photography. Picasso, I’m fairly sure, had a portfolio. But they are uncommon to the point of being unheard of in scientific fields, like research and technology. Einstein, I’m fairly sure, didn’t have a portfolio.
But at some point over the last decade, a clueless recruiter or employer asked a user experience researcher for their portfolio. In a panic, the job candidate pulled something together and now it’s just seen as a given that a UX practitioner will have a portfolio that illustrates their work — even if they don’t create visual designs.
Other people have waded into the debate over UX portfolios (Timothy Jaeger in particular makes very salient points, as does Megan Kierstead here and here), and yet here we all are, being asked over and over to submit portfolios before a hiring manager/HR person will even speak to us.
Congratulations UX, and welcome to your much desired seat at the table! You sang the praises of your precious deliverables for so long that now, that's all anyone cares about. Great success! We're now reduced to production monkeys -- well done!
So, allow me to try and turn back this horrible tide of mediocrity, and poor hiring practice. It all comes down to one very simple fact: 98% of what a UX practitioner does is invisible, and results in the 2% you can see (wireframes, prototypes, sitemaps, personas, etc).
You're absolutely terrified now, aren't you? Good.
The value of a User Experience professional exists entirely in their ability to analyze, critique, and understand a problem space. Anyone -- literally anyone -- can draw a wireframe and make it look beautiful. Deliverables have zero value without analysis and understanding.
If you're speaking to a UX practitioner who has spent time in an Agile environment (hi!), then we don't even make deliverables as a hiring manager understands them. The last time I made a wireframe was in the summer of 2014. Between September 2014 and June 2016, my design work consisted entirely of whiteboard sketches with my team, or dirty edits of existing screens in PowerPoint (I was a Product Owner, so I wasn't given Photoshop) to solidify an idea the team had discussed, and add it to Jira for a user story.
More than that, in true Scrum fashion, design of our product was a team responsibility. No longer was I UX Moses bringing down the Wireframe Commandments from high atop the Design Mountain.
And I have to tell you: it was a relief. For the first time, I was sharing the work with other people, and helping them learn how to think through flows, and experiences, with the eyes of a customer. This, I thought, is how design ought to be done.
My UX portfolio has any number of deliverables, but they have no value apart from the context, and stories, of how they came to be: the client and team I worked with, the challenges we faced, the victories, and disappointments. When you ask to see my portfolio without hearing the stories, you're missing the stuff that really matters: you're missing the 98% of what I do.
Anyone can make a wireframe, or a sitemap. It's honestly not hard, and god knows that there are plenty of overly fetishized tools out there that make them really pretty. But does a person know how to think, how to fail, how to pick themselves up again, how to work past blockers, how to work with a team, how to sit with a problem and chew on it until the edges become familiar?
You will never find those answers in a portfolio, friends. You will only find those answers by talking to the person. And isn't that what we tell our clients? You have to do user research! You can't just look at your data or stats or reports! You have to understand the people buying and using your product or service.
How ironic, and sad, that we've forgotten.