I think the node statement is about being able to look at your own copy of the blockchain and verify transactions. If you're checking on mempool.space or somewhere else, that data could infact be tainted - but... whatcha gonna do?

I agree, most people never will and we should not expect them to. Self Custody is more important than running a node, in my opinion.

When you aren’t running your own node; you are broadcasting your activity on someone else’s node.