> mistakes that made clones possible

You mean like publishing the system board schematics and a full source listing for the BIOS?

That seems to have been surprisingly normal for PCs in the late 1970s.

Apple also published schematics and listings, and had to deal with clones, but Apple 2 clones weren't particularly useful without a copy of (or compatible replacement for) Apple's ROM, which Apple did not license.

Protected under copyright law, and not allowed for cloning just because.

I am 70's child, kind of aware how common it used to be during those days.