I'm not sure I understand. Why would rebasing ever be more complicated? They're the same thing at the end of the day, no? Main branch and my branch both changed this line no matter what, you must resolve that conflict.
No matter how complex your branch gets or how much it diverges from main, you'll only ever need to resolve a conflict once. For rebasing you may need to resolve conflicts multiple times for changes you may have made hours/days/weeks ago.
If you're strict about rebasing and keeping your working branch clean and remembering what you were doing in that commit from three weeks ago the rebase process might not be that bad, but it can never be easier than a merge.
Rebase conflicts are like short-selling stocks; there's no upper limit on how bad it can get.
I never rebase a feature branch on top of the changes in the main branch. The branching point of a branch always stays the same.
But I use rebase for editing commits in my feature branch all the time, i.e. I rebase interactively one feature-branch commit on top of another feature-branch commit.