Because the data is linked, you cannot easily extract a single file from the middle of the archive without WinRAR processing everything before it.
In a multi-part set (like .part03.rar ), if one part is corrupted, it is much harder to recover data from the subsequent parts compared to a non-solid archive. How to handle it
Updating or modifying a solid archive is slower because the software has to re-analyze the entire data block.