In many cities, poor people occupy valuable urban land close to downtown jobs, amenities, and transit. They can afford to live there because the housing stock in inner areas is usually older. If it hasn’t been completely renovated, the result can be quite cheap, even if the land is pretty valuable.
In areas where there’s already some gentrification pressure, landlords face a timing problem: they can renovate (or sell to a developer) now, and cash out. Or they can hoard the property and wait until prices rise, supplying low-cost housing in the meantime.
Land value taxes are specifically designed to penalize the hoard-and-wait approach by raising the annual tax cost of sitting on valuable land. It is specifically designed to accelerate neighborhood change. That’s the point. That’s what it says on the tin.
Gentrification isn’t the only urban problem, and maybe it’s a small enough urban problem that a land value tax is a good idea anyway. But I think most of the benefits of Georgism can be unlocked with George-ish schemes (like renovation abatements or vacant land taxes) that are more narrowly designed.