Very informative article @gavvet. I surely learnt a lot.
To add to what you have said, So many of us have the wrong impression of ferns, including me - I thought that giant Staghorns weren't really ferns but some sort of epiphyte more closely related to bromeliads or tillandsia.
Any plant that starts from spores is classified as a fern.That includes the unfern-like Staghorns, skinny Horsetail and many other seemingly alien plants.