There’s no real onus to provide a source that something does not exist. Blizzard doesn’t share precisely how their bot tracking works, so it is possible that the 30 instance limit does help with it.
There is even some evidence that it does.
This is the extent of the evidence that supports it though, and it isn’t clear that that’s even what is being claimed by Kaivax in this blue post.
So, one possible interpretation of this is that running more than 30 instances in a 24 hour period to farm MCPs is exploitative (though, I personally think that interpretation is ridiculous).