The G5 has a guaranteed spot, so if they stay in the range of top 10 or 11, where they would have received an at large bid anyway, it theoretically results in one more at large bid being available for a team like BYU.
Same with the P5 conference champions that don’t make the playoff (P12, B12). It is in BYU’s best interest for all of them (with likewise guaranteed NY6 bids) to stay ranked ahead of BYU, rather than coming in from lower in the rankings to steal what would have otherwise been an at large spot.