It's completely pointless as an addition.But replicator don't need pops who then can do other things (for example - working in forge world with ancient refinery) AND can produce Rare resources like valuable (in terms of sell price) Zro, or Nanites. Replicator is not used as alternative to refinery, but as addition.
It's sort of like how, with Nanotech ascension, you can get nanites from sources other than the starbase building... but so few that there's no point whatsoever.
The Replicator gives so few crystals/motes/gas that it just doesn't matter. It doesn't give enough to supply, for example, researchers when they start needing it, so you WILL need the regular buildings, which don't require additional pops to work those jobs (just to supply minerals) and produce multiple orders of magnitude more of them.
The niche the Replicator does still have is producing resources you otherwise can't normally scale up, but for the basic three strategic resources it's essentially pointless. You will already have enough production to make it irrelevant and it will not replace that production so you'll still need it.