Depending on how you count Heaps, BYU has had a future NFL QB on roster since 2006 or 2012. Not the same as the late 70s for 20+ years, but good. Heaps was paid as a practice squad QB by 3 NFL teams (future NFL QB on roster since 2012, if you exclude Heaps, since 2006 if Heaps included), Taysom, Hall, Wilson, Slovis. All except Heaps had contracts to play. All made rosters.

When you aren't P4/P5 a highly rated QB will think long and hard about signing for a team with a future NFL QB already on the roster with years of eligibility left. ZW and Hall left with a year of eligibility, so highly recruited QBs were very hesitant to sign with no way to know they would both leave early. BYU signed Slovis and BYJew together, so if Jake goes to the NFL the team will have had 2 NFL QBs on the roster together for 2018, 2019, 2020, 2023 and who knows about 2024. Please find non-P4/P5 teams that have had 2 NFL QBs on the roster for 4 of the previous years (assuming Jake gets some NFL time - may be a bad assumption, but seems possible). 2 NFL QBs on the roster for at least 3 of the previous 6, if you exclude BYJew.

QB recruiting is not BYU's problem. As others have inferred, all teams recruit high school players, but many teams only do so half heartedly/ with half the effort the did pre-NIL/ pre-transfer portal. Much easier, much less risk to recruit players in the portal or recruit players to go into the portal. BYU has had great success mining Weber, USU, BSU... for starting positions.