We often see technology from the future brought back to the present, whether as a case of a chance encounter, or something more.

However, it’s also fairly uncommon to see those technologies pop up against after they’ve been introduced. One such example is the ablative armour generators that Admiral Janeway fitted to the Voyager, being prototypes from a future Starfleet, which are seen in that episode, and then never again, even in shows that are set after the time she left.

The reason for this might be that the Federation does not want to run the risk of being accused of violating the temporal prime directive (or accidentally running afoul of it in some other way), and shelves that particular technology entirely.

From their standpoint, it would be rather difficult to separate a technology that the Federation developed of their own accord, compared to one that they might have developed from being inspired by, or reverse-engineering a piece of future technology, so they shelve it, rather than risk the trouble, never developing the preliminary steps to reach that future technology.

The only anachronistic part of this is the Doctor’s mobile emitter, which is a variant of 26th century technology, and was developed into Picard, but that can be explained by it being reverse engineered from 26th century technology, by someone in the 20th century, technically making it technology from the past. Since it is Earth technology from their own past, they might be able to get away with iterating on their own version without risking trouble with the various temporal enforcement agencies.