Why not?

It’s supposed to be fun. As long as you’re not cheating the global leader board - which this approach doesn’t - why not play however you want.

I like go to overboard writing parsers for each day.

From the about page: "... However, you should do Advent of Code in a way that is useful to you, and so it is completely fine to choose an approach that meets your goals and ignore the leaderboard entirely."

Is there really a wrong way to do it?

Ha! Yeah, imagine me streaming my working on AoC, basically anyone tuning in the stream would say 'you're doing it wrong, stop having fun!' and leave.

my guess is that the creator would almost certainly disagree with you