An interesting observation which I have said for a while.
Because so much housing is so high, it is out of the reach of many lower income people. By necessity, they are living in manufactured homes and because there are now more and more people who cannot afford to even look at anything newer in stick built, they are opting to look for affordable housing and a manufactured home is more affordable and thus the pool of buyers is growing as wages stagnate and stick built prices escalate.
As a secondary consideration, newer manf. homes are often better built although we'd rate their quality at or below "starter home" levels. And again, MHs are extremely popular out of regulated city limits. I often wish I had a MH instead of stick built at my age. Being on the farm, my heirs will have an issue of what to do with my house. We have no one at the age they will need a house. So, if my home was a MH, they could simply sell it and be shed of the unit and let the yard revert back to pasture.