But so are assassins and thieves :P I'd say I see 2-3 assassins/thieves for every warrior online - they aren't exactly lighting up the PBF stats ;).
I just don't agree that STSF is OP - there seems to be a lot of evidence to the contrary. Having played alongside Liantae for hundreds of hours, I know he was very aggressive. Jarlduz was dead before I got to take a stab at him or play with him. Out of the top 10 PK'ers of the last 10 years only one is a STSF build (thanks gabe for the new feature).
I think part of the popularity is that a lot of fights are 1v1, which allows for many chances to escape while allowing STSF to build - I also think that is where Jarlduz capitalized on his burst damage build (entwine+sigil+drum+imperial offense/tactics..dayum). I think that toe to toe a burst damage build will still give STSF a good run for the money. I will try and prove it to you :)