why do you assume people who refuse a rematch are scared???????
I'm not scared of a rrrrematch! Brrrring it on!!!!!
What time controls do you use? Especially for longer games, many players like to look over and digest a finished game before moving on to another one.
Aside from that, it's possible that your opponents may have started another match before they got your rematch offer.
Well challenge me somebody if you dare!
But be warned -- I BITE! >;3
Boring!