Nul points?

Very much a case of - which came first, the chicken or the egg?  The producer of the Eurovision Song Contest has accused the late Sir Terry Wogan of totally spoiling the contest by poking fun at the contestants and their songs.  He makes the point - quite correctly - that back in the 60s and 70s, the UK invariably used to be there or thereabouts, but then things changed and we became one of the also-rans. However he seeks to connect this with the fact that it was at the beginning of the 70s that Wogan took over presenting the show and, as he sees it, his rather irreverent style of commentary convinced the British public - and the BBC - that the Contest was not to be taken seriously and not worth putting any real effort into it.  Of course, you could equally well point out that it was around this same time that "performances" started to become more important than the songs, and tactical voting became more blatant.   So was Wogan the cause, or simply reflecting the reality?