alt Hacker NewsNobody gave you the actual answer. IBM was under an antitrust decree and had to openly license their technology for a nominal fee. (Supposedly about $5/PC.) So yes, they were in a hurry and used generic parts, but they still had tons of patents on it. When they got out from under this, they came up with Microchannel.
This and also cryptography technology was not nearly as sophisticated and easily accessible as it is today, and where it existed it was pretty slow on the hardware of the time.