Smaller files are easier to manage and move across different file systems that may have size constraints (like FAT32).
If even one byte in "part25" is corrupted during download, the entire extraction process for the whole game will fail. game-way.of.the.hunter-(62677).part25.rar
Many cloud storage providers have a maximum file size limit (e.g., 2GB or 5GB per file). Smaller files are easier to manage and move