In fairness, they did that too, with Biden. I also sent messages to all my congresspeople back when they were voting on aid for Israel (not that it did anything). Putting pressure on Harris at this point to pull her towards the side of humanity in her forming Israel policy does seem like some level of sensible thing to do.
I absolutely think that the level of pressure the activist left has been putting on the Democrats has been producing an impact, which is absolutely a good thing. Pretty much the only part I disagree with is the attempt to solidify some sort of linkage as if the Democrats like what is happening in the Middle East right now or have explicit policies in favor of it, that aren't posited on pure political survival in our misled and largely war-criminal-friendly electorate.
Best I can do is a bunch of DC consultants whose clients are all 120 years old who will say naw this is a one-off.