Oh christ, that dA page someone linked to, the OP of the MS paint picture of a bolter and a Halo rifle is trying to use Draigo as a counterpoint to the fact that Master Chief killed the covenant with his rifle. Oh, and using the term "real man" when
both the characters being discussed are genetically modified and arguably no longer human.
Many palms and many faces must have met.
On the subject of the Ork shoota, I'm surprised none of us pointed that out yet. I guess it was because it was table as, er, a tabletop question rather than fluff, so it took someone smarterer to spot there was a fluff argument to be had as well.

In terms of maintenance though the bolter is able to operate without maintenance for some time, especially with caseless ammo as caseless reduces the number of moving parts that have to move. But at the end of the day no firearm will operate for long without it. Barrel fouling, general wear and tear, or just corrosion of the metals would strike eventually. Even AK-47's need to be cleaned, parts replaced, and parts repaired over time.
Orks however do have the advantage of being Orks and not believing in maintenance, thus not needing it. They think it'll work, so it does.