Its been 11 months since people figured out that sin/shadow was op. The only reason they havent been nerfed to the level the should be in PVP is because they still have to have them as the 3rd viable tank for PVE. Its as simple as that. Try to get people to look at the birdie all you want, fact of the matter is sins are/have been/will be OP in PVP as long as this game is around.
Lots of assertions, few of which are even related. Lumping all assassins into a single category and then labeling them OP may be easy for someone lacking a firm grasp of game mechanics, but it isn't really reflective of reality.
Deception/Infil wasn't competitive until very recently (and still isn't imo)-- nobody played it competitively because it was a terrible spec, even with FS/Resilience. So your inelegant assertion that all assassins have always been OP is as ridiculous as it is wrong.
Your beef, which you seem unable to properly articulate, is probably with high damage and utility hybrids having access to 5 second resilience of FS. This is a far cry from all assassins being OP, but in order to know and have argued that you'd have to be less bad than you clearly are.
Incidentally, immunity to force and tech is not the same as immunity to all damage. I suspect you also have a beef with not hitting the keys you want in the order you want and having your opponents fall over.