Why can't the brain and nerve cells heal and other tissue can. there must be an evolutionary disadvantage?

Our body is made up of cells in which transfer of message between  cells takes p[lace by intercelluar liquid called matrix .if damage any of your part the matrix between it get destroyed ,but our brain  is able to able get recover some of it ,but not all result in incomplete healing of that part and we cannot recover fully.

It's lithogenous i believe of course i looked it up.

Yeah, i guess that checks out because the unused brain is almost like a clean slate or a new car. it has more value than an older already used brain. -thomasnash