On: M.2 SSD Can Self-Destruct by Giving Itself a Burst of Voltage

seems unnecessary with encryption

You know, sometimes security through obscurity works. If you can't find all the pieces you certainly aren't going to retrieve their data.

Just flash/flush the embedded encryption key, the SSD remains usable with a/the new encryption key. This just seems like a way to increase sales...

You can be compelled to give up encryption passphrases, either through legal process or by force. If that data is irrecovably and provably erased, that is no longer an avenue for access.

put part of the symmetric encryption key in volatile memory