Why only between the years 1987-1996?
Because in 1997 the card manufacturers began the 1-of-1 idea. 1997 Fleer Showcase to be specific. If you scroll through the main page there's a link titled: "Why 1-of-1's Shouldn't Be Considered Tough". If you find the subject interesting enough please feel free to read my opinion, then afterward come back here and continue with my explanation. It'll make more sense. <wink> ;-)
Back? <g>
So once the manufacturers killed the hobby completists, a group many of us once belonged to, I realized that it would be pointless (not to mention impossible) to attempt to build a "complete" or "master" collection beyond 1996.
Of course, over the years I continued to collect Thomas cards, but I stopped trying to collect an example of every card produced. Even today you'll find me bidding on and trading for recent Frank cardboard, but for sanity's sake my "official" collection begins in 1987, with Frank's first ever card, and ends in 1996, the last year it was possible to make a complete collection.