The Wither passively regenerates from killing plant life near it

Since the premise of the Wither is to spread its decay in the world, it makes sense that it gains 5 hearts of health every time it kills any living entity; however, nothing directly explains its continuous passive regeneration.

It would be a subtle, but interesting addition to automatically kill plants just by just getting close to them. In a 7 block radius from the wither, the grass should turn into soil, leaves into air, and flowers, grass, crops, and any other plant material should briefly turn black before disappearing. Wood and mushroom variants should be the only plant materials not affected by this. 

This would introduce an interesting game dynamic where the player should consider the amount of living things nearby when fighting the Wither. The more plants the wither destroys with its presence, the quicker it should regenerate, making the fight more challenging.

On a final somewhat related note.

• Fighting the Wither in Bedrock is more interesting since it involves more strategy. I think it would be amazing to implement some Bedrock mechanics into Java, like the summoning of skeletons and preventing undead mobs from burning during the day as long as the Wither is alive.