Providing advanced technology is not a good idea. Help them improve the design of replicators and the like, sure. But just giving it to them doesn't really solve the problem... and would likely just embolden them to keep being aggressive.Well, see that's the thing - replicators supposedly can take any matter, break it down and recombine it. It doesn't need to be something special like deuterium. So they could literally just supply their replicators with chunks of planet to make whatever they wanted. Further, wouldn't it make sense, as a gesture of good will to their neighbors, for the Federation to provide more advanced replicator tech? Would that not go a long way to preventing others from using the scarcity angle as motivation for aggression? Seems a great opportunity to stabilize relations between empires.
And as Tallguy mentioned, land is something that can't be replicated. As populations keep increasing, where do they go when every planet is getting full?