Of course any and all exterior doors should have a door sweep. His reasoning is ridiculous.

Job security for installer.

You can go to your local Home Depot and get the sweep to put on your door.

Disclaimer - I have no language skills when it comes to door construction so sorry this is not a very technical answer:

It should absolutely have a sweep to keep weather out of your home. I don't believe sweeps are designed to protect the door itself though. Hopefully others can comment on how the bottom of the door should be finished. I would think more than priming. Shouldn't there be another strip of material that covers the bottom so you don't see the two gaps in the door construction?

Those grooves at the bottom of the door, the sweep glides over that. Pretty easy to put on as these get replaced over time.

Exterior doors should be completely weatherstripped. Please add a photo of the threshold and weather stripping system.

Ok, due to conflicting information from Masonite reps, it seems these doors can go with or without the sweep. The builder says many times they hold water due to a lip that shows at the bottom of the door. He suggested cutting the lip so sweep is flush with the door.

Builder also said they don’t always apply a sweep because of the water issue.

Thoughts. I certainly don’t want to have to replace another door due to wood rot. Here is a picture of previous door with rot.

All of which goes to make my point even more that the Jeldwen doors are crap (just like there windows). What would it take to design and develop a door with a $4 pc if plastic door sweep that does not hold water. Absolutely ridiculous.

There appears to be a rubber "sweep" on the bottom of the door but the photo is dark

" Thoughts. I certainly don’t want to have to replace another door due to wood rot. Here is a picture of previous door with rot. "

Looking at this last picture further, the sweep did not cause that door to "rot", the poor design and the fact that the door is sitting directly on the deck did. I prefer to see the door with at least a small step so the water does not pool there from a wind driven rain. That exposure with no sweep is going to give you fits, mark my words you will have more issues than door rot.

I would prefer a door with a sweep as it should cut down a bit on air infiltration and insect intrusion.