It's not a scapegoat, it's basic economics that wages are determined by supply and demand; increasing the supply decreases wages. It's also basic economics that this ultimately reduces costs to consumers, but that doesn't make it any less painful for the workers whose wages face downward pressure due to increased competition from labor force growth.
Never heard the words "basic economics" used outside of strawman political arguments. To think that H-1B developers can meaningfully shift the supply to the point that is felt by other people it's very shortsighted. The job market has been very difficult for years with vastly more supply than demand and its due to plenty economic, financial and political reasons. Interest rates itself affect it way more than any H-1B developer could ever do it. If you were to actually sit down and look deeply into it and look at the data, I'm sure that H-1B would be a small percentage of the problem and you would get fired up about so many other things.
But that's difficult and time consuming, if anything it's advanced economics and requires effort to decode what's happening. What it's very easy to do is getting angry at a group of people and to feel deep unfairness about it, then think that if that group of people were to leave, the problem would improve or be solved. That's exactly the kind of thought that seems to be so pervasive at all levels and yes, it is a scapegoat. Especially since that the only merit someone has over H-1B is to (by pure chance) having being born in a different place. I really feel that many people complaining against H-1B wouldn't even qualify for it if they were born somewhere else.