Yeah it confuses me when I meet backend developers who can't deploy their app for example.

If you can't:

a) Tell me what libs your app requires & how to install them in a resonable way b) The privledges required to run said app c) The security implications d) How to scale your app, particularly what I need to do to get it to behave over multiple servers e) be resonably sure your code is working f) Write some code to automate the deploy of this.

Then you're probably just not that amazing of a developer.

Plus I think there's a big difference in respect a full-stack team / tech leader garners over someone who doesn't really understand the technical challenges of half the team.