[Retric]

"tetrahedral beings were flown both unmanned and manned during a five year period from 1907 until 1912" So, according to the article they did carry people.

An important consideration is these kites where lighter per lifting area so they needed less wind and would also fall slower without wind making them somewhat safer. The added redundancy is also an important consideration.

PS: It's actually fairly easy to build a kite that can lift a person in a strong wind as even a simple parachute will work. see: parasailing which can work at even 15mph. The problem is finding a design that fails safely.