Theymos could've solved this problem the time he created the merit system.. He could've easily given every member merits based on activity and not ranks, for example: A full member like you who has 250 activity should have been given around 200 merits to start with not only 100 (the amount needed for member rank).
But he must have his reasons not to do so...

.....I considered giving merit proportional to activity, but I decided not to because doing so would probably give far more undeserved merit than deserved merit in total. But undoubtedly some people got screwed by this.....