Ad Rank is a function of bid and QS (heavily weighted towards CTR). Adjusting weighting of any of the three public components of QS will impact all participants

Ad Rank is a function of bid and QS (heavily weighted towards CTR). Adjusting weighting of any of the three public components of QS will impact all participants, ignoring cases of exceeding max bids, all bids should increase proportionately-- with some participants having different impacts, but overall a net increase. Bid floors will exclude ads from showing unless a certain ad rank is met. If users want to continue (or start) receiving impressions, they need to meet the adjusted threshold. This won't be as common on terms like "chicago movers", but when you get into the longtail and use an Alpha/Beta structure, it can be relatively common to get a "bids below threshold" for lower volume terms that have less (think <5) auction participants as shown in search insights & sampling the SERPs manually. When you get into these niche terms, you assume terms will be cheap due to lack of participants, but that isn't typically the case.