Did bike manufacturers mix and match Shimano components a lot in the 1990's?

In 1998 I bought the only brand new complete bike I've had since I was a kid of 13 - a Carrera Virtuoso road bike, Tange Double Butted tubing, frame built in Taiwan. To be fair, I haven't ridden this one much, it's got angled straight forks and every vibration goes straight into my wrists, so I tend to prefer the older classics I've built since, which are lighter, more comfortable, faster and look better.

However, this came as standard with a mix of Shimano components - RSX 7 speed STi levers & derailleurs, RX100 chainset, Exage brake calipers & hubs. It all works perfectly together, smooth, lightish action and snappy. I've put Tiagra and Sora on some other bikes and they feel slightly sluggish in comparison. None of the above can hold a candle to 105, which after all is only a mid range group, but can be bought cheaply in good condition on ebay. I've never ridden Dura Ace but must try this soon.

For top bikes though, I feel the only way to go is Campag - Chorus, Super Record or Record depending on year - or even Centaur on a newish frame. Can't define exactly why, there is an element of prejudice to be sure, but it just seems more solidly built and finished.

Anyone got views on this I can learn from?