The treaties do not change the underlying principle, though. They change the application of them, in that the only way for parliament to breach the ECHR for example would be to leave the treaty, but that is no different from other laws - the only things that is different is the complexity of the process of doing so.

So, yes, it's more complex. I don't think anyone would suggest parliament would just rewrite arbitrary laws on a whim, because there are complex dependencies (hello Brexit). The point is there is no legal hindrance to it, and that is almost unique (I write "almost", but I don't know of a single other country where parliament has so unfettered power - I'd love examples).