Would it be possible to play the game off a USB Flash Drive?

[Soukyuu]

You could have just googled it ~.~

Googling doesn't automatically equal in a good explanation of the matter.

Here's a quote from a technical note:
"Read Disturb: A read disturb error occurs when one or more bits are changed during a
READ operation. Read disturb errors occur within the block being read, but on a page or
pages other than the page being read. Performing a high number (hundreds of thou-sands or millions) of READ operations on individual pages before an ERASE command
for the block containing those pa ges can exacerbate this error."

From what I'm reading here, this error occurs when you try to read and write simultaneously, with writing disturbing reading. So my argument stays valid, FFXIV only reads from the flash drive unless it's
a) patching the files (no read operations to disturb)
b) saving logs or macros (which are not stored on the flash drive but in the my documents folder)
c) downloading patch files (see b)

[Coldfire]

From what I'm reading here, this error occurs when you try to read and write simultaneously, with writing disturbing reading.

That means you didn't understand it.

[Soukyuu]

That means you didn't understand it.

That means you didn't explain it good enough. Shall we continue?

[Coldfire]

That means you didn't explain it good enough. Shall we continue?

I didn't explain anything. I gave you the definition of a flash memory manufacturer.