One thing I have noticed watching eBay for BRIO catalogs over the years is that there seems to have been a major transition in 1992, and again in 2001. If you look at the BRIO dealer/consumer catalogs from the 80's up to 1991 you'll notice that they are all "full" catalog books: the complete lineup of BRIO products are shown inside, ranging from infant toys all the way to role play toys aimed at older children.
Beginning in the year 1992 and running through 2000, there don't appear to be any of these full catalog booklets at all, however. Instead, what you see are specialized catalog books that focus on the individual product lines. For the purposes of this blog, what I am most interested in is the first Wooden Railway system catalog book which appears in 1992 along with its companion photo book. You'll also note that 1991 is the first year that the modern foldout/brochure mini-catalog insert appears. Coincidence? Probably not. In 2001 the product-specific catalog books start to disappear and the full catalog book returns. There are no Wooden Railway-specific catalog books to be found after 2001 until the overhaul of the BRIO Wooden Railway system in 2010.
This change in the way catalogs were done in the 1990's would make sense. You can think of the 90's as being the golden age of the Wooden Railway system as this is when sales were increasing rapidly, peaking in the late 1990's. Wooden Trains, in both the BRIO and Thomas the Tank Engine lines, were extremely popular toys driven in large part by the Thomas and Friends TV series. Why wouldn't it have it's own catalog, particularly versions of it that could be distributed with the large and popular starter sets in order to drive more sales? The full catalog book, in the mean time, was not abandoned entirely: it was merely shrunk down into little inserts that were placed in (neary) every retail package, a practice that continues to this day.
Of course, all of this is just observation and guesswork, and a theory that conveniently fits the information at hand. But just because something isn't seen on eBay, that doesn't mean it doesn't exist. If you know of a full catalog from the years 1992 to 2000, I'd sure like to hear from you.