Because its a lot less fiddling getting it setup to run those 1000 rounds.
To the OP:
You can buy a gauge to test your rounds. (Wilson and note, its very tight so you have to judge a it bit). Most of mine stick up a bit (depends on brass) so I do the following, take down your gun and use the barrel chamber as a check.
I have the Wilson but as noted I know how much mine stick up when still ok.
I crimp in a separate step and I do just enough to get a snug but not hard feel. Light crimp
Some books say no crimp and some say a lot, hmmm.
Issue is the head space, so if it slide into the chamber ok its ok.