In article , rgammon51
@yahoo.com (Robert Gammon) says...

Hardie Panel or Hardie Plank both are heavy paper coated with cement.
When they are in long term contact with moisture, they will fall
apart. Nailed to the frame, there is NO air circulation, so if
moisture gets behind the siding, it will fail.

Failure to prime the backside was a common, almost universal building
practice here in the early 1980s. Almost all of these homes have had to
have their siding replaced as a result of the builders NOT following
mfg's directions with wood siding.

You are missing the point. Cement based siding has been on the market
long enough for the first wave of house repairs to start coming in. It
has become obvious that you do NOT attach cement board siding directly
to the sheathing. Cement board siding WILL draw moisture, particularly
on the north side of the house, causing rot in the sheathing and
framing. The way to avoid that is to install thin furring strips to
space the siding off of the framing enough to provide air circulation
between the siding and sheathing. Lath will work, but most installers
now use 1/2" treated furring strips.

With proper ventilation behind the siding, back priming is not
necessary.