I think it's both and. Role based works well in some cases. Task based well in others. It's a false choice to think you have to pick one or the other all the time.
This is where prompting comes in. You need to remember to tell it about which libs you want or encourage it to web search to find the latest ones, or use something like context7 MCP to get the latest versions.
Hey -- sorry was out of town so didn't see this! It could definitely work without Linear. You'd need to modify the command for the linear stuff to just write to MD files and make sure you pass those through to the other agents.