The myth probably comes from a bit of truth. While holding left stick fully down never shut off the motors you did risk your phantom going into vortex ring state because it was coming down too fast and washed any "good" air out from under your props and phantoms did fall out of the sky (Google vortex ring state it's too long winded to go into now). Over a year ago dji through firmware updates reduced the descent speed so VRS didn't happen anymore. I'm sure it is still maybe theoretically possible but we don't hear of it on phantoms that have the descent speed limited but even when if happened the motors never shut off.
Blimey .... all that in one breath ?? No commas ... full stops .... ??
No offence intended - just had to read it and put my own stops in !!
Nigel