Often, a client or your company has an idea about how something should look or function regardless of research, prototyping and testing. I’ve seen the process take place over wasted weeks just for a client to say, “Yeah, but that’s not what we wanted or envisioned. Make it like this or make it fit somehow.”
That’s when I’ve seen products and services fail spectacularly while the designers and researchers ask themselves, “What was the point of all that work then?”
Edit: There’s also kind of a branding problem with design strategists where, as someone else pointed out, a lot of them are just good at packaging and presenting mediocre ideas into really slick powerpoints and presentations. And many of these strategists even present themselves as very artsy and slick and can spout off very woo-woo lines of magic and dazzle with their charisma. It gives people who are exposed to these designers the impression that they’re all just a bunch of snazzy consultants who offer no real value.
Have seen quite a few "designers" who drinks the koolaid of design sprint, design thinking, etc by asking everyone what everyone thinks the product should look like, then proceed to prototype a frankenstein that "addresses" everyone's concern. Not once did it end well