Except "the far left" != Democratic Party any more than "the far right" == Republicans. So, no, the point is to condemn the Democrats for not condemning the few (a couple) far left just like the Republicans had to condemn the few (a couple) far right they have. One could argue this reasonable tit for tat, I guess, but it's pretty absurd to argue the Democrats are anti-Semitic when they're the ones being constantly hounded because they seem to go overboard on taking any possible offense at words used to conjecture anti-Semitism/anti-gay/anti-black/anti-woman was intended.
Reading that is quite horrible, although it sounds like the issue is she followed a user who themselves have posted hateful things. Should she, if she disagrees, remove that person from her list? Yes. Does the fact that one person you follow says horrible things automatically make you an anti-Semite? Or that you get funding from people who are anti-Semitic? By the same logic if I replace "anti-Semite" with "racist" would that still hold? The point isn't that I believe Rashida Tlaib isn't anti-Semitic. It's that the standards you're using to decide this have to be consistent.
As for retaliation and self-defense, it sounds like Tlaib was saying that Democrats and Republicans alike are Islamophobic, not anti-Semitic. So, who was making the claim that Republicans were anti-Semitic? Is it self-defense to not refute the claim against you but claim someone else is equally bad with another religion/ethnicity? Is the issue that we care about only some groups and not others? Is the outrage that a Muslim said horrible things, not a white guy? Or was it because it was in Congress and not at the State level? I tend to think it's the last part.