Abyss blink doesn't really affect many areas that sin are good at so your idea that abyss blink is OP is kinda false.

You don't typically take a sin in for inferno cows which is really the only end game area in which tele can be used. To make sin viable, it is hard to give them MF, which is wanted for inferno cows.

Sins are also only viable if you have all end game gear and enchants while a lot of the other classes are viable with their respective set items or minimal end game gear / enchants.

Yes sins are great when you have all end game gear and max enchants, but so is every other useful build. Shadows are squishy AF. Sin has relatively low life for a class that usually is getting attacked. If you are a pure trapper, compared to other ele builds, it is relatively harder to reach the needed - Res.

Again, sins are great, but you need all the best gear in thE game for them to be viable.