I think you might be misreading "don't be afraid to get your hands dirty" as "go poking at stuff for trivial reasons without following any proper process" instead of "don't offload parts of your job to other people out of fear".
I imagine that, if an engineer at Pacemaker Incorporated is given a task that's touching an area they're not comfortable working on, the author would suggest that "sorry, talk to Alice" is not a good attitude while "okay, but I'll need to go through some training, do you mind if I reach out to Alice for mentorship?" is.
I recently spent a couple of days tracking down a problem that one of my coworkers, who built the subsystem where the bug was lurking, probably could have figured out in an hour or two at most.
Why didn’t I hand it off? Because I need to know how this subsystem works. It’s important and quite complicated and this is not going to be the last bug we have, or the last change it needs. It’s part of what I work on so I should understand it. The payoff wasn’t just fixing the bug, it was learning enough to know how to fix it.
I imagine that, if an engineer at Pacemaker Incorporated is given a task that's touching an area they're not comfortable working on, the author would suggest that "sorry, talk to Alice" is not a good attitude while "okay, but I'll need to go through some training, do you mind if I reach out to Alice for mentorship?" is.