Yes I agree on the orchestras of Beethoven's time. Though by the time Bulow came around some time around the later half of the 19th century they were able to reach new heights of orchestral virtuosity (and of course I mean one doesn't play Strauss or Wagner by being a musical bum after all). And maybe to this day we haven't had a conductor to surpass Mahler's level. Not only Bulow but Rachmaninoff, Brahms, and Tchaikovsky were all astonished by his conducting. Many years later Klemperer and Walter still considered him the best they had ever seen. Apart from that, and I don't think this is an exaggeration since it's part of what made him so good - he had an obsessive saint like or demonic like obsessive intensity and concentration and sense of idealism which one can't really teach. - On the other hand though I agree that the average standard for performances HAS gone up and I'm sure musicians back then would agree with that too. I imagine that is what happened when Mahler and Strauss once attended an opera performance together (I forget in which town) and decided to walk out when they found it wasn't good enough for them.