We hired someone like this, thinking their “street smarts” would give them an edge and make them a good employee. What happened instead is that they struggled

We hired someone like this, thinking their “street smarts” would give them an edge and make them a good employee. What happened instead is that they struggled with discipline. They were late to client meetings, they missed important deadlines (rest of us had to pick up the slack), you name it. They were indeed street smart and stood out in terms of creativity, but their lack of what is typically called “work ethics” (which no doubt contributed to their average GPA) prevented them from meeting their obligations. So yeah, GPA isn’t everything but it can be a really good signal for qualities necessary to succeed in professional work.