Oberth's are honestly better as Logistics Support vessels than anything else.
They're not supposed to be front line anything.
Maybe the Oberth class was originally conceived as a ship that wouldn't be usable on the front lines... however, that was in the 23rd century.
As technology advances, and ships are upgraded, their capabilities improve over time - that means less need for support craft as all ships in Starfleet tend to come with high levels of automation and self-repair systems anyway.
If it wasn't discontinued after 'Generations' movie, the Oberth class may have received a large 24th century refit to fit in with the times... their primary function would probably still be support, but they would have vastly improved range and could probably stay closer to frontline ships to provide support if its needed and even do stand-alone exploration themselves too.
Look at the Nova class for example.
It was originally described by Janewasy in the following manner: " It was designed for planetary research, not long range tactical missions."
In VOY episode 'Endgame' we saw the USS Rhode Island (another Nova class starship) which packed quite a punch, seemed to have been very fast, and was able to quickly disable two Klingon Negh'Var class ships - so it seems that because of the said upgrades, the Nova Class was able to do deep space exploration (as Harry Kim was away doing just that on the Rhode Island for 4 years) and long range tactical missions now.
It suggests that SF vastly improved on the Nova class capabilities which were still in active use 26 years later... at least in that timeline.
It seems that initially conceived starships that had 'limited use' received upgrades which radically expanded on their overall capabilities.
In the 23rd century, the upgrades would have added some functions to the said ship and improved overall capabilities, but probably nothing along the lines of what 24th century tech could do.
So, if the Oberth is still in use, my guess would be that much like the Nova class, it received internal and external upgrades which made it more suitable for use in the 24th century.