Time locked puzzle for payment in Lightning Network

Currently HTLC’s timeout transaction relies on absolute timelock enforced on the script. It allows a counterparty to withdraw the money from the contract if the other party doesn’t release the preimage. What would have been the problem if instead of using timelock before the counterparty can unlock its money, the condition is replaced with timelock puzzle? The time taken to solve the puzzle will be same as the locktime of the offchain contract.