They are setting it up as their default position. However, like anything in the contract, it's up for negotiation. One example, some sellers will want you to pay the dues for current or banked points. However, you may be able to negotiate that out. Some sellers insist on buyers paying closing cost. Other times, they may be willing to cover that.
A reasonable position might be that the cost is split. Or, the cost may be borne by the buyer, but there's a lower $ per point cost.
Realistically buyers will have to take the overall cost of the contract into account ($ per point, annual dues, closing costs, any middleman fees, etc.) and decide overall if the contract is still worth it. This will impact smaller contracts to a much greater degree than mid size to larger or more expensive contracts.