I tend to agree with this but then I am also old enough to remember shows in echoey venues that were never designed with acoustics in mind, back in the day. Stadiums and civic centers and auditoriums with lots of reflective surfaces combined with not so great gear to create less than optimal sound conditions.I've been going to concerts and such since the 70's. There has always been a great deal of variability in the quality of sound at such things. Incompetence will always product lousy sound, but the good concerts (which seem to be more frequent nowadays) are, in my opinion, much better than they were back in the 70's. The quality of PA gear, and the knowledge and tools to set it up well, are far better then they were decades ago.
I think that today you have far less of those things. Even stadiums are more optimized for acoustics because they are designed with the understanding that those things will happen there. They weren't back in the day.
Gear has made things easier, too. The quality we get at reasonable price points really wasn't obtainable 35 years ago.
But you will always have inexperienced humans at various stages of the music-making process.