Even back when comics were fun, they weren't always easy to figure out. Take Captain America for example. He had several different versions of his origin story by probably 1975. They all were basically the same, but they had minor variations to them- vita rays, a potion to drink, a serum that was injected. Add to that the fact that his costume and shield changed by his second issue with no explanation given (years later it comes to light that it was an agreement to avoid litigation over a similar company's character "The Shield") and Cap's history was a bit confused.
In this issue John Byrne and Roger Stern take it upon themselves to tie everything together. This was before the idea of shield being made partly of vibranium was ever introduced, so they always kept it as a "metallurgical accident that couldn't be reproduced.
Retcons can be fun, and this one really is, since it takes existing ideas and binds them together properly. I'm still annoyed Bucky is alive now.