They were most likely just bugs. Quite possibly really stupid bugs.
Not every bug results in the program doing the wrong thing, they often just make the program do the right thing very slowly.
And nobody notices, since it still produces the right result.
Yes, they were bugs, I think programmers (and their marketing people) were more focused on new features than performance
Thankfully we’ve moved past that era.
Now the bugs that get ignored for new features cause bad results AND bad performance.