Sealer does add texture, that's the elephant in the room. I guess a "painter's painter" can lay it down like glass, but even then there is an extra layer of material that needs to shrink as it gives up solvent, resulting in at least a small loss of gloss. The best sealed jobs we end up doing are when the new e-coated part goes on a vehicle that has clear coated jambs, in which case I will just go ahead and seal, base and clear the whole part prior to installation on the vehicle. The magic happens when this cleared finish is sanded flat and the exterior based and cleared again on jobs that need it for color consistency. The second time, very little base is needed so the clear lays smooth and shrinkage is minimal. Probably what makes it work is there is usually at least a couple days between the jambing and repainting. I wish I could do them all that way!