I was a pro sound guy.
You would probably be surprised by how badly people can and do adjust levels between different patches. Additionally, level matching varies from gig to gig. What works for a loud gig may not work for a quiet gig. This is also true for tonal balance and how much of the wet signal should be used for different effects. So for each gig, as a player you really need to be able to step through all of your patches and adjust level, wet/dry, tone, etc.
Unfortunately, there tends to be sort of a circular aspect to this problem. You make a change to your patches and this forces the audio tech to adjust. Then the audio tech's adjustment may force you to make another change...on and on.
Maybe the OP is the rare exception and knows how to quickly mitigate these problems. And maybe the audio tech has been burned by several people who do not. It's also possible the audio tech was an idiot or lazy. I don't really know as I wasn't there. About all I can say for sure, is the problem is probably a lot more complicated than some of us seem to think it is.