It doesn’t make sense that cities need to increase property taxes every year though

Property tax revenue should be increasing every year by default without changing the rate simply because houses and properties increase in value every year typically

If property tax is 5% and the town makes $100,000,000, the next year if property value increases by 5% then their revenue goes up 5% as well to $105,000,000 automatically. Why do they need to also increase the tax to 6%?