The modern, electrically powered versions of steam shovels are used only in very specific situations, such as mining.There are many examples of this phenomena where a new, niche product arrives in a targeted market, but then expands until it reaches up and rips out the guts of the companies making the previous products. 

I think a bit of hesitancy on the part of developers can be good, because one of the phenomena that happens is that developers are too industrious and ambitious, and they overbuild, creating a huge glut of supply in a market downturn, making landlords want to pull their hair out. 

The unwritten rule but my observed phenomena just like @?

I think the problem really is the "too good to be true" phenomena in real estate financing.

When you compare costs for a used 16x80 and add in the cost of locating it, moving it, rehabbing it, the used home often ends up costing more than a new one assuming you are looking for a late model vinyl and shingle home.The types of deals that existed in the early 2000s were a one-time phenomena that may not happen again anytime soon.

It's true because it's a mathematical certainty, not some phenomena related to the skill of real estate agents.

Because the house hacking phenomena is relatively new there is very little relevant guidance in case law.  

There is a phenomena of credit score inflation at the moment because of college debt deferment.

In fact, it's a well known phenomena for newbie investors in general. 

That’s a recent phenomena in SF RE.