An "Accepted Answer" means something different on each Stack Exchange site. On some sites it's a functional question; this solution worked, full stop. We have a more subjective case.
When should a user accept an answer? When their curiosity is satisfied? When the community seems to have come to a consensus on the validity of an answer? Only when peer reviewed research supports an answer?
Obviously when to accept is up to the user, but I think it make sense to have a guideline so we can evaluate whether it's acceptable for users to have very low accept rates.