ezo
Where is that Singe?
No, they should have some impact, just not the overwhelming one they have in 5E. In prior editions with larger "proficiency bonuses" (attack bonus +10 to +20, save bonuses up to +12, etc.), the +4 or +5 bonus would be felt but not as much of the total. In 5E, with proficiency bonus +6, that +4 or +5 bonus nearly matches it.Leave ability modifiers for ABILITY CHECKS, rest uses prof bonus instead of ability bonus.
That is, AC, DC, attacks, damage, saves all uses prof bonus.
While I understand the desire for bounded accuracy, 5E is too bounded. Ideally, keeping (about the same) +4 bonus for ability, proficiency should scale up to +8 to +12 at least.
For homebrews developing "D&D games" with lower maximum level, doing a simple +1 per level would work. Capping PCs at +4 ability modifier (at least at 1st level) would match as well.