Merits are already enough. Implementing like just for those who doesn't have sendable merits would just simply eradicate the idea of meriting. Why? Merit already boosts someone's confidence when he/she receives one (a rewarding-like feeling for your efforts), and "Likes" on the other hand tends to give you the same feeling and worse is some can be boastful about it (if calculated on one's profile). It is not that necessary to implement a "liking" system for a forum that already has a better one.
Your right mate,Merits system is like the man power of the community and implementing another law is not really obtainable in order to favuor those who don't have sendable merit is not encouragable, because i understand that it's because of adoption of merit system that is making the community to be competitive and also interactive in terms of discovery, so given alternative to merit will make it lose it's potentiality or regards from my perspective, the existing policy is highly adorable because any amount of merit earned determine the amount of user sendable merit.