Rebase early and often and this isn't an issue. Some see this as a chore, but I view it as taking advantage of the tool's power. You resolve the same set of conflicts as you would merging, but (as you say) earlier.
Edit: I don't think anyone was trying to imply a single allowed feature branch at a time; we can probably all easily agree that's basically no different than working on master.
Yes, rebase early and often works great. But if your branch includes a major refactor, your going to find yourself editing others code to get your rebase to work. That just increases your own scope. But yes, rebase often is often a very viable strategy. In practice though, I find very few that actually do it because it becomes painful when your branch lives too long simply because business isn't ready to ship something
Edit: I don't think anyone was trying to imply a single allowed feature branch at a time; we can probably all easily agree that's basically no different than working on master.