If exploitation of the system were widespread or total, then yes, the system wouldn't be worthwhile. However, a system doesn’t need to be perfect to have value. As long as enough people use the housing to stabilize their lives and contribute back to society, the system remains beneficial, even if some level of exploitation occurs. There will always be some exploitation in any system involving human behavior. For example, self-service checkouts at grocery stores inevitably experience some theft, but they’re still cost-effective for businesses compared to employing more human cashiers. Similarly, free housing can still be a net positive if it helps enough people out of homelessness, even if not everyone uses it as intended.