Using a naive supply/demand optimization, that's true. But housing is a hyper-local market, and you have to apply that at a local level instead of a macro level.
Areas with more supply than demand already have easy access to home ownership. If someone's goal is just to "own a home", then they can already get one for 0% down by moving to a rural area[1] or an impoverished metro[2]. Even with no capital requirements at all, these areas struggle to attract interested buyers.
Areas with more demand than supply are already building as much additional supply as feasible within the the localized constraints (which could be geographical/physical, or could be governmental/zoning). Decreasing upfront capital requirements from 20% to 5% increases the size of the demand pool, but the supply was constrained even before those new entrants. So the increased competition will just result in pricing appreciation, as the existing demand can use that 15% spread in additional capital they have to out-compete the new entrants to the market. While some constraints are artificial (such as zoning) and could be removed to increase the available supply, those empowered to do this are the existing residents of the area who are enriched by this price appreciation. So they're perversely incentivized to reinforce this imbalance in supply/demand, rather than to take action to correct it.
There are likely some localized markets with more supply than demand (or the ability to increase supply in the face of increased demand). And these would react as you expect, with lower pricing available to maximize that demand. But this situation is transient in nature, as the more developed an area becomes the more likely they'll run into natural supply constraints (or have artificial ones introduced). So it'll eventually lead to one of the above situations: they have too much supply and have to essentially beg people to move there, or too little supply and pricing appreciates in response to the new demand.
Areas with more supply than demand already have easy access to home ownership. If someone's goal is just to "own a home", then they can already get one for 0% down by moving to a rural area[1] or an impoverished metro[2]. Even with no capital requirements at all, these areas struggle to attract interested buyers.
Areas with more demand than supply are already building as much additional supply as feasible within the the localized constraints (which could be geographical/physical, or could be governmental/zoning). Decreasing upfront capital requirements from 20% to 5% increases the size of the demand pool, but the supply was constrained even before those new entrants. So the increased competition will just result in pricing appreciation, as the existing demand can use that 15% spread in additional capital they have to out-compete the new entrants to the market. While some constraints are artificial (such as zoning) and could be removed to increase the available supply, those empowered to do this are the existing residents of the area who are enriched by this price appreciation. So they're perversely incentivized to reinforce this imbalance in supply/demand, rather than to take action to correct it.
There are likely some localized markets with more supply than demand (or the ability to increase supply in the face of increased demand). And these would react as you expect, with lower pricing available to maximize that demand. But this situation is transient in nature, as the more developed an area becomes the more likely they'll run into natural supply constraints (or have artificial ones introduced). So it'll eventually lead to one of the above situations: they have too much supply and have to essentially beg people to move there, or too little supply and pricing appreciates in response to the new demand.
[1] https://eligibility.sc.egov.usda.gov/eligibility/welcomeActi...
[2] https://detroitmi.gov/Portals/0/docs/HousingAndRev/2018/Resi...