[shiroiushi]

>I think there's a fourth, which in my opinion is even more world shattering than the others -- the replicator. It often was shown as a novelty device to make food or warm beverages, but the ability to convert energy into any needed material would instantly transform the world into a post-scarcity, post-economic future.

IIRC, in Star Trek, the replicator does not convert energy into needed material: it simply reorganizes existing molecules into a new form.

So, for instance, you can't use it to make yourself a bunch of gold: you could use it to convert a bunch of gold jewelry into gold bars, or vice-versa, but you would need some actual gold. It won't convert lead into gold. I think I heard or read somewhere in the lore (maybe non-canon) that the food replicators needed supplies of biochemical ingredients to use for making food. They could get that from various places, including breaking down the waste of the crewmembers, but they couldn't just conjure food out of nothing using pure energy.