Most of the time such meaures aren't being taken, and water vapour is
being put into the air all the time a house is occupied. Heating
enables it to carry more water vapour, but obviously that alone
wouldnt keep it dry for long,

Obviously it would. With the thermostat at 20 degs the air will carry
more water than you can produce by breathing and cooking. That is
precisely why it isn't a problem for normal people in normal houses.

It's interesting that tropical hardwoods grown where the RH is damned
near 100% dry out too quickly when they are felled. It's all about
temperature

there is then ventilation which
replaces interior air with greater vapour content with outdoor air
with lower water vapour content.

How much vapour content there is, in or out, depends on temperature. You
can't just say that the interior has a higher vapour content.


In walls without a VB, you also have higher water vapour content on
one side than the other, so the vapour slowly migrates through the
walls from inside to outside.

Its basic physics.


Fortunately the average housewife knows perfectly well how to keep a
house dry and healthy without your in-depth knowledge of physics.

You continue to adopt this high handed and patronising attitude to
anyone that disagrees with you, which I don't find at all constructive