You see I'd go with your argument but Sunderland's still got great poverty *despite* Nissan - it's been a fraction of what was lost and far more than around these parts, which is still well down on its heydey despite JLR and a couple of others. In a general sense it suffers a bit for being number two to Newcastle - it sees the investment go there, and Newcastle becoming fashionable and feels left behind. You get that in other places too - Swansea to Cardiff for example. Go outside a bit to the likes of Darlington and it gets worse... and it is fair to say that as with about the whole country, there's a feeling everything is London-centric. In many ways Johnson had the right idea with levelling up, but the fact it hasn't actually happens magnifies the issues.
So yeah, I'm not denying that feelings about immigration contribute, but if everything else were well there'd be no need to blame other groups or communities. You're right (assuming it was you! Apologies if not!) that people look for a reason and a target to make it easier to understand and explain, even if that target isn't a fair one.
At the same time, current disturbances are clearly being stirred by people who don't want to try and come up with the answers. To a degree it might be best to ignore them and focus on those who are vulnerable to their message, and what we can do to stop them being indoctrinated / radicalised.