Should an opensource dev know Linux

[techlists at phpcoderusa.com]

Hi,

I'm a PHP developer and always thought all opensource developers had at 
least some knowledge of Linux.

Recently I watched a YouTube video that stated otherwise.  The presenter 
said it is important to know Linux which will set one apart from the 
crowd.

I have been "messing"/"playing"/"working" with Linux since around 1998 
or so. Learned a lot and have a lot to learn.  Thought all opensource 
developers had at least a fundamental understanding of Linux.

Is it true most do not know Linux?

And is it true that it is good, for a dev, to be able to put they have 
basic familiarity of Linux  on their Resume?

Thanks in advance!!