Sorry to keep hammering on this, but ... I don't know in what context it would be reasonable even as a simplification to say that block ciphers are semanticall

Sorry to keep hammering on this, but ... I don't know in what context it would be reasonable even as a simplification to say that block ciphers are semantically insecure like that. Anyone who listed that as a disadvantage to block ciphers should be regarded as confused, not speaking from a big picture perspective. Furthermore, even if you're going to explain it that way as a result of building up the complexity gradually, you need to explicitly "unring" that bell, e.g. "Earlier I said X, but actually Y...". This author didn't.