We will just have to go with our experiences then. My belief is 'cycle' bacteria resides mainly in the filter. In a cycled nonplanted tank the general guideline is you can change 1/3 of filter media without causing a minicycle. As far as people replacing HOB cartridges that IMO is a great way to cause a minicycle if the above guideline is not considered or the new cartridge is not run alongside the old one for a few weeks.
Given my experiences I can take a brand new tank, sensitive tetras, and just a fistful of mature media and have an instantly stable tank up and running with no issues. Generally these tanks are totally bare bottom and may not even be a actual fish tank, but a storage bin. I have never had much of any issues cloning a tank for instant use and keeping all ammonia and nitrite 0 from day one. The only way IMO to do this is with mature media as it contains most of the good bacteria in a mature tank. Again the above rule is still applied, the donor tank if non-planted can loose 1/3 its media without disrupting the cycle. That media you take can support roughly 1/3 the bioload from the donor tank. As long as the receiving tanks bioload is within that there will be no cycle. The only tank I own these days that can donate any significant amount of bacteria is the very heavy stocked 55 I posted above. While it is heavily planted I can still clone a bare bottom tank from it without any issues.
I've changed substrates a least once on all my tanks and its never caused a minicycle. Most my tanks are going to soil substrate tanks these days. I agree that their is a lot of bacteria in the soil and it takes time to colonize, yet such bacteria are not relevant in the basic cycle. There will be some cycle bacteria present all over the tank, but it is not a big enough proportion to cause a minicycle if it is all lost. There are multiple ways to run a tank though. For example a planted filterless tank works because it replaces most of the cycle bacteria with plants. Over half of my tank are not filtered or do not depend on the filter, because the plants uptake ammonia not because the bacteria are elsewhere, they are simply not there in significant numbers in the first place.
Perhaps some food for thought is on another forum I use, members offer up mature filter media to be mailed to newbies that find themselves in the middle of a fish-in cycle. It is viewed as an assured way to help speed up if not stop 'new tank syndrome' or do a fishless cycle in 1 or 2 weeks instead of 3 to 4. If good bacteria does not exist mostly in the filter then this method would not work very well yet it has been successful and running for 6 years now. You must also factor in the % of bacteria lost and such during mailing though that is pretty minimal.