With due respect, I believe the statement above is inaccurate, because it is directly contradicted by Bitwarden documentation, which spells out the locations where the (encrypted) vault is stored on the local computer:
For example, for my Bitwarden desktop app, the vault is currently stored in the file C:\Users\grb\AppData\Roaming\Bitwarden\data.json.
I am not advocating the use of an encrypted Excel file (for the reasons you state), I offer this comparison only to make the point that without documented information about how the local vault copy is encrypted, we have no way of knowing whether it is any more or less secure than an encrypted Excel file (which, by the way, uses AES256 encryption, so is reasonably secure if a strong password is used).
Moreover, Bitwarden apps remember the PIN used even after the computer is rebooted, which proves that the encrypted PIN must be stored on disk as well, and I believe that other credentials may be stored on disk if one chooses options like disabling “Lock with master password on browser restart” or setting the vault timeout to “Never”.
Edited to Add:
Here is another thread in which the OP (@Jmac ) reports he was able to copy the locked data.json file from one computer and unlock it on a different computer; the thread also includes a good discussion by @rpaulson about the inconsistencies in the available documentation):