Honestly, point seeking behaviour of people writing answers was one of the worst anti-patterns of SO. It would lead people in later years to quantity over quality (especially because of the bonus 15 rep that OP could give you by "accepting" an answer in addition to upvoting it). Worse, it would incentivize them to answer terrible questions that should have been swiftly closed and then deleted when OP inevitably failed to do anything about them. Instead, getting an answer in before closure would prevent the automatic timed deletion system from removing those bad questions.
Quality answers come from intrinsic motivation: from people wanting the site to be a place where people find quality answers. (Something I didn't personally understand in the early days is how important a quality question is to finding a quality answer.)