Things always evolve.
Without investigating,
it feels like haiku,

written more strictly,
don’t break up separate thoughts
on separate lines.

On the other hand,
sonnets can be much more strict
without doing this.

The stricture of both
would yield an intense pressure
when mixed together.

Integral numbers
of haiku would never fit
Inside a sonnet.

It’s really too bad
because it would be awesome
if that were the case.

Instead, you must write
eight haiku that are complete
and then you are stuck

with four syllables;
Unless you write a sonnet
Ending with the word

Etcetera.