What is the rationale of promising to not reapply? If a company is hiring again 6 months after some layoffs, what would be wrong will rehiring an ex-employee wh

What is the rationale of promising to not reapply? If a company is hiring again 6 months after some layoffs, what would be wrong will rehiring an ex-employee who was one of those laid off, assuming they are the best candidate for the new job opening?