Yes, agree with all the replies above. No, LH can't be held responsible for every aspect of decline at the other group carriers, that's true.
But I do remember hot meals in economy in the time period 2006-2010 on practically all OS flights, and they were pretty decent, not the small cantine dish offered now. I mean, that pasta dish doing the rounds is not even economy class level. After that time period, I believe there was a period when OS offered BoB which wasn't particularly popular. Then normal, free catering came back and I think economy hot meals were served on flights of over 2h30 duration. Could be quite wrong with all of this, but for me OS now is as different to what it was before in the same way that a Nestlé KitKat bar can in no way be compared to what it was when Rowntree Mackintosh was an independent company. Bad comparison, I know, and you may correctly argue that flight ticket prices have come way down over the years. But the decline in service is far too much and I reckon that the European carriers are as bad as, if not worse in some cases, than their American counterparts.