I do have the advantage of one lab back in college where a pro spent 90 minutes instructing a bunch of teenagers how to prepare Gerbers for a class project through Advanced Circuits, but beyond that I've had no problems sending files to OSH Park, JLC, PCBWay, Sunstone, or Advanced Circuits whether they were generated in Eagle, Kicad, or Altium.
Even at the low-margin providers like JLC and PCBway they still have a human look over your gerbers (and most provide web viewers for you to see what you've uploaded in those files) to make sure you're not going to order the inverse of your board, or make all your vias unplated, or swap your copper and silkscreen layers, or anything goofy like that. If you do screw up the design, that's on you and the tools won't help, but prices are dirt cheap and turnaround times are screaming fast these days, so it shouldn't be too bad.
I don't understand why newcomers find plotting to gerbers so intimidating.