"Since you not only have to hold the room with creep alone"
i think most (if not all) of S1 and S2, top20 players can own a sector for themselves
that means that the 2-3 rooms/sector are quite untouchable by anyone else for scoring due to limited TTL of claim-body creeps. Only 'disrupting' might be possible, but still that would mean that player would probably have to sacrifice his/hers score-defence (since not owning a sector)
That alone would mean that the gap between top-players and everyone else would be huge.
With every room possible to score, there is still option for mediocre/new players to participate in some way, allows some agreements like in S1 to mitigate weak-player wipe, and there would be some more creativity with army of smaller claim creeps over big area or focusing on holding fewer more worth rooms with bigger claimers