This is a problem for any Civ that has a UU that requires a resource. Any of the the civs that have say, a single UU ~ if any one of them require a resource, than they suffer the same problem as Rome ~ the inability to use their UU if they lack the resource.
Picture Rome without UUs ~ They're Still screwed in the ancient era if they don't have Iron.
The problem isn't the inability to use their UUs, it's the problem that they don't have access to iron, period. Which imo is the equivalent of lamenting about Elizibath being trapped far inland on a map ~ It's bad luck - her UA is made irrelevant as is one of her UUs. All it means is that a part of Rome's power, like many other civs, is dependant on how well you roll on your position in the map.
Any civ with a UU that requires a resource is obviously at a disadvantage if they don't have that resource.
Agreed, but more so if both require the same resource, and even more so if both require the same resource in the same era.
Rome without iron would still be screwed in the early era if they didn't have iron. But becaue both of their UUs require iron, they're affected in two ways:
1. They don't have access to a core portion of classical armies (swordsmen and catapults) and have to rely on on archers, spears and cavalry.
2. They don't get to use either of their UUs at all through the entire game. They essentially become a civ without UUs.
Any other UU that relies on a resource of course could end up in the same position. But if a civ has two UUs that require different resources, it is extremely unlikely that they don't have either of those resources. They therefore do not suffer the same fate as Rome.