Britannica actually had a great website during the dot com era - hyperlinked, very browsable, and definitely had that semi-addictive "rabbithole" quality.

The hurt themselves badly by imposing a really annoying paywall just as Wikipedia was beginning to take off. A hybrid model with tiered access (maybe even a limited ad-supported free tier) might well have kept them on top - instead, they offered only a single expensive annual plan priced to compete with the paper or CD editions.