What's up with these SB's (typically young to mid 20's) who state they seek "friends with benefits" and "platonic".  How can you have both?  

Many do not know what platonic means, I have explained it to a couple when talking with them.

your money, and the benefit they will offer is that they will read The Republic to you.

...Seinfeld.  
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Neither did I, but that's different.  
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Life is good.
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The Cat

platonic
a relationship between two people that entails no sexual feelings nor lewd thoughts but rather plainly just being friends with the person.

Some do actually say they are open to platonic or physical.  

Have come across a few using both fwb and platonic where their words suggest the benefit is being able to spend time with them or for them to be your arm candy. Those profiles quickly get hidden….

One story is that Plato, 81, died in his bed, whilst a young Thracian girl played the flute to him.  No indication of what sort of "flute" she had her lips wrapped around.  However the age difference would suggest SB/SD.

1.  They are open to either
2.  They want to initiate the arrangement as platonic and then evolve into FWB
3.  It's cover in case someone they know reads their profile
4.  They haven't a clue!

I don't know about the Plato story but I do know that "flute girls" were in the middle of the hierarchy of prostitutes in classical Greece.  Flute girls would perform at parties as singers, dancers, and musicians and, once they were on the premises, also provide other entertainment for a price.  The pornoi were the lower end girls who worked outside the city walls, mostly doing sex standing up.  The hateira were very pricey, I gather because they were willing to assume exotic or unconventional positions for sex.