Sharing my work got me, as an Aussie working mediocre jobs, on the right person’s radar to help me land a job at Facebook. This shaved probably 10 years off my career path. That was a great return on investment and a big leveller for someone who didn’t study at a brand name US college and have an obvious path to the door of a major tech company.
I’m now in a position to hire others. I certainly don’t mind if someone doesn’t have open source code shared. It clearly not a priority for many people. But I do appreciate when people do have a good backlog of work to show as it can give a seemingly lacklustre candidate a second opportunity to shine.