I can understand skimping $40 on a book... but not the argument that it was hard to find those things.
If you had read the article you would have seen that there is a lot of dynamics behavior going on that is essential for the gameplay, but mostly unrelated to the A* search itself. I don't think you would find many books from the 80s about pathfinding for RTS games.
In the 80's and 90's you were lucky to dig up docs from BBS releases that had math and graphics tutorials in them, it was very hard to find anything practical.
The tricky part is on assigning nodes on a contiguous map or reducing number of nodes. (Or expanding node resolution on demand.)
Of course many games of the time side stepped it by using greedy truncated pathing instead. Easy, dirty, mediocre results.
About the only thing necessary is to stabilise pathing so that it doesn't return vastly different path on every tick and handling inter object collisions well. This may mean additionally handling swarm movement algorithms for which were already known way back in early 90s. Also in widely known books.
Games like Total Annihilation handled fast movement of hundreds of units at a time with decent to good pathing and a strong enough CPU - scaling the quality of pathing automatically with available CPU power to boot. Way better than AoE and it was released at about the same time - plus it has actually smooth terrain penalty unlike AoE chunky model underneath...
Three challenge was rarely algorithm but instead engineering. Time crunch was as real then as nowadays.
Anyway, the path finding feature is not finished once you have a graph traversal solution. Routing large armies with formations, varying unit sizes, dynamic terrain and collision detection remains fairly challenging in practice.
The whole section of pathfinding is very weak, and doesn't mention A-Star at all, nor any refinements to it that have been developed over the years.
I used the book as an example of commonly available piece of literature from 90s, not as best source.
Requiring everything to be given in any easy and digested form is actually a weakness... and it might not even save time.
Having read a few books that were explicitly game oriented, none of them tackled big problems efficiently. Either they threw out vague ideas (no better than the actual algorithm book, often worse) or they fixated on the specific game.
Websites are no better nowadays. No depth and no breadth inn most of them. Stack Overflow is the epitome of no depth.
Toy get much more mileage by reading and understanding say Knuth's books than any gaming relayed book. Despite them not even roughing the subject. Now for details, true, access to actual papers and research is very useful, but I bet few game developers have that anyway.
The trap as in most rushed development is that you will choose the wrong direction then get to live with consequences. Internet does not help with it as one cannot properly communicate a problem you can't solve, and once you do the solution is almost always known. The best you would get is a set of recommendations which is most useful if you're completely green...
Time, experience and experiment trumps slightly better sources 9/10.