The issue here is that these people aren't providing value. Further, engaging with them as serious and sincere costs in time and energy. That's expensive when there's no payoff. From my own experiences, beg bounties reliably do not have findings of a useful quality and the begging approach is a very strong signal that the juice will not be worth the squeeze.

The piece is gatekeeping in the same way the spam filters we all use are gatekeeping. There's always stuff we want to keep on the far side of our filters. Beg bounties are among them for many.