"You don't think this is a result of decades long fucked up relationship between US and Israel, driven by almost all political and administrative entities from both DNC and GOP, and not just Biden?"
You are mixing up "the way it is" with "the way it should be". They are speaking to the way it is not trying to argue that it should be that way because we always have.
It's simply stating a fact. The US has a multiple decades long bromance with Israel and the unsettling truth is that we both love doing the whole industrial war machine killing and genocide thing. A lot. Slavery, Trail of Tears, Vietnam, Banana Republics, Tuskegee, Iraq, Afghanistan, and on and on. And you're gonna sit there and tell me it's Biden's fault alone that Israel is doing a genocide? And that he alone can somehow stop them after decades of doing it too and backing them?
Should Biden denounce the genocide? YES
Should Biden at least stop sending munitions? YES
Should Biden send in our troops to stop the IDF? Yes? No? Maybe? I don't even know.
Is he responsible for the genocide? NO
One thing that makes me bristle at the situation is that a lot of people are saying “he is doing the genocide so let’s elect Trump!”
And one thing that makes me bristle is when people assume that all opposition to the genocide is this. My position is that Biden is supporting Netanyahu's genocide and that he should stop.