That's a valid question. If this operation was being done in a large milling machine (40 taper or 50 taper), an end mill would be a good choice.
Lots of flat-bottomed holes are needed while hole-making on the drill press. It's near impossible to find a large end mill with (for instance) a 5MT shank, which is common on a large drill press. So you grab the drill size needed, cut off flat in the abrasive chop saw, grind relief behind both cutting edges, and you're ready to go.
I'm just lookin' at all the dings on the taper.
Where I last worked, that drill bit would be considered pristine, given a score of 10 out of 10
In a production shop, expendable tooling is just that - use it hard, use it til it's all gone, get another to replace it. Grab a 1" bit with a 3MT shank, put it in the 3MT-5MT adapter, whack the end of the adapter
HARD on the drill press table (or lathe compound, or on the top of a thick metal bench), drill hole, wedge the adapter off (which often sends the bit to the floor) & drill something else
Pretty tooling doesn't pay bills, but lots of holes, drilled in a timely fashion, pays the rent... and a busy shop drills dozens, sometimes hundreds of holes per day. You don't get yelled at for breaking the occasional bit, or putting dings on the taper -- you do for being slow.
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Barry Milton