5-over-1 are increasingly common and not the same thing as soft story buildings.

5-over-1 refers specifically to the wood construction of the top 5 floors. You can have a soft story building that is not built out of wood and even more vulnerable to earthquakes.

5 over 1 has nothing to do with the number of floors. It means type 5 (wood) over type 1 (concrete).

Looks like while some people agree with you, it's not the most common use.

> The name derives from the maximum permissible five floors of combustible construction (Type III or Type V) over a fire-resistive Type I podium of one floor for "5-over-1" or two floors for "5-over-2", as defined in the United States-based International Building Code (IBC) Section 510.2.[1][4] Some sources instead attribute the name to the wood framing of the upper construction; the International Building Code uses "Type V" to refer to non-fireproof structures, including those framed with dimensional lumber

https://en.wikipedia.org/wiki/5-over-1

It’s debated, but the prevailing belief is that it originated to refer to the number of stories. Hence you’ll also see “5-over-2” used fairy commonly as well.

The canonical "5 over 1" has a very solid concrete base. Hence the name.

From the article: "5-over-1 construction—so called because it frequently combines up to five floors of inexpensive wood-framed construction over a concrete podium—is popular primarily because it is a cost-effective means to build, especially here in timber-rich Oregon."

It's a mostly new style.

In addition to the sibling comment, the recent rise of 5-over-1s is largely attributable to the use of fire-retardant wood in order to comply with fire codes.

5 over 1 doesn’t necessarily imply a Soft story building. In many cases the bottom floor is much stronger than what’s above it.

Most of the buildings of this style that are going up around me have steel framed first floors and wood above. The elevator and stair shafts are concrete block to help protect fire escape routes.

Not sure where you live, but in my own US city they went from non-existent (as far as I recall) 20 years ago to literally everywhere I go. There's probably 4 going up within 3 miles of my house right now. Maybe that has to do with more stringent firecodes. Only thing close are the row-houses where there's 3-5 units, narrow, 3 stories high with a roof deck (I don't know what they're called).