You can’t do that because it will physically fall apart. That’s the main issue with boosting it up higher and just leaving it there. It was never designed to be existing for a thousand years, and eventually wear and tear will make the station naturally break apart. It’s significantly more dangerous for small fragments to drop over time as compared to a deorbit and decomm. At least the deorbit is planned, while the disintegration would be pretty random and not fun to deal with.