Can S-Rank Mastery scores be awarded the full amount?

Would it be too much for S-Rank Mastery scores to be given the full amount of Mastery points even if you lose?

I just finished a 50 minutes game as Maokai, went 15/7/14, and achieved an S-Rank that gave me 71 Mastery points...feels bad, even though I did well enough to achieve an S-Rank. I think it'd be fair for S-Rank scores, given they are supposed to reflect a player's exceptionalism with a champion and as the maximum level achievable from a game.

Why not award the player with the full amount win or lose?