PDQ wrote:
My cabinetmaker did a fine job of future consideration when building these cabinets.

That's not what he was thinking of when he built them that way. While
it worked out well for you, most flooring is not run under existing
cabinetry. I installed tile, hardwood, and vinyl professionally for
several years.

Nowadays, most mass-produced cabinets, regardless of the size of the
shop that built them, are built like yours. It's done for shipping,
installation, and parts-standardization on the shop floor reasons. Many
installers might mount them a tad more elaborately than yours are,
especially if the sub floor isn't that level or well-built.

In older, and some new high-end stuff, the newer it is, the higher-end
it will be to see this... it's common to see extremely high quality
cabinetry and built-ins that are either built in place right on site, or
permanently assembled in place. The builders will go to great lengths
to hide fasteners, too.

Some "average quality" stuff installed in very well settled (read
"whacked", not-so level floors) antique homes is much easier to install
on plywood toe-kick bases that are blocked and shimmed level before the
boxes are set. Last summer, I did a small kitchen in a 1740's home that
would have been a nightmare without separate bases. The same house had
3/4" t&g SOLID MO-HOG (probably Cuban) bathroom walls that a previous
owner plastered over!