If dynamically typed languages are really okay for smaller systmes, than avoiding bad architecture of large tightly-coupled systems in favor of loosely coupled compositions of smaller subsystems means that it is also okay for large systems.
It doesn't mean that at all. You might as well say "if shoes are good enough for going to the corner store, then multiple pairs of shoes are good enough for going to the moon". The notion that large systems are no more complex than small systems if you simply make the large system out of small systems is not supported by anything I can find.
IME, that's why they've historically been harder to read and navigate for humans
That doesn't make any sense at all. How is having information written down instead of having to constantly remember and/or deduce it an impediment to reading?