I'll stick with T5 makers over MgT fabricators.
A maker is a 3d printer+++
As to the Third Imperium, the TL15 high population industrial worlds manufacture the vast majority of the goods sold within the Imperium, and there is nothing a lower TL world can do about it.
It would change trade too, IMO. Why bother shipping finished items when you can transport bulk fabricator feedstock for manufacturing at the destination?
Makers do have limitations.
Size - a maker can only make stuff up to a certain size, this may be ameliorated by making parts that are then assembled.
thing maker - has the widest range of maker sizes
ship maker shop - for spare parts, pus can act as a thing/gun/armour maker with the correct programs and feedstock
gun maker
armour maker
vehicle maker
synthetics maker - robots, cybernetic parts, clones, bioroids...
ship maker - limited to ACS.
Feedstock - the maker requires ingots of specific alloys, polymers, elements. Makers tend to make the least complicated version of stuff, but with the right programs and feedstock may make much higher quality stuff.
Specialised components - it is often much faster to have dedicated manufacturing for things like chips which are then used in the maker construction process.
Time - makers are not fast, it can take them a lot longer than a fabrication plant dedicated to manufacturing one particular item,
eg an ATV fabricator will make an ATV a lot faster and to a usually higher standard than a vehicle maker
Energy - makers use a brute force approach thanks to the plentiful supply of energy from fusion or fusion+, thus dedicated fabrication plants will produce cheaper goods.