I have a 1993 Trek 5900 OCLV, their top of the line road bike at the time. It's still fine. Fork is heavy by contemporary standards, partly because it used a steel steerer tube. The forks appear to be all carbon fiber, but very tightly compacted to the dimensions of typical steel forks. With a newer style hollow fork and carbon fiber steerer, that bike could still be built up to around 17 lbs or lighter. The steel steerer is the single heaviest thing on the bike. Origin8 and a couple others still sell those style forks -- carbon fiber forks made to the dimensions of older steel forks, with steel or aluminum steerer tubes.
My nearest LBS is a longtime Trek dealer, since the 1970s or early 1980s, with the original owner still in charge. He was so surprised to see a decent 5900 OCLV after so many years we chattered for about an hour. Usually he'd try to sell me a new bike, but he seemed so impressed by this one we just talked shop and looked at old catalogs. (I bought some stuff anyway, as I usually do when I visit that shop -- tubes, whatever.)
Very different from the larger dimension but hollow carbon fiber forks with carbon fiber steerer tube on my 2014 Diamondback Podium. When I got that bike second or third hand I disassembled the fork to examine the steerer tube, headset, frame headtube, etc., to be sure everything was okay. The fork has a nick on the paint on one side, apparently due to scraping it against something while leaning, not due to crashing. No problems.
Coming from an old school steel bike background, I was a bit concerned about both bikes at first but after plenty of miles on some rough roads, no worries now. I've cracked some rims on 1980s super light low profile aluminum rims intended for mountain stages (Wolber Super Champion Alpines, Araya CTL 370), but haven't managed to harm these carbon fiber frames or forks.