Why are strong acids and bases not suitable as primary standards?
strong Bases in general are not suitable as they will react with $\ce{CO2}$ from the air. This is actually more problematic than hygroscopicity, as it means that you also cannot store diluted $\ce{NaOH}$ solution (openly) as standard.
Instead, $\ce{Na2CO3}$ or $\ce{KHCO3}$ are much better alternatives (for strong acids).
The acids are either a gas ($\ce{HCl}$) or are produced from gas. I don't see how you can produce a conentration reliably enough for use as primary standard.
even if you would manage to produce saturated $\ce{HCl}$, it's much more difficult and less reliable than known alternatives (see below).
but that wouldn't work e.g. for $\ce{H2SO4}$ as $\ce{SO3}$ is soluble in $\ce{H2SO4}$ (Oleum).
$\ce{HNO3}$: redox reactions are not only not particularly useful, but actually harmful as they use up acid equivalents:
$\ce{NO3- + 2e- + 2 H+ -&gt; NO2- + H2O}$
also here, a solid alternative (KH-Phthalate) is available. If you don't have that, you may get away with oxalic acid which is still better than the acids suggested here.