Why is Tide so popular?

Eli Lehrer informs me that Tide has a high market share even though it is more expensive than most other brands.  This source says the market share of Tide is about forty-four percent, with the sum total of all Proctor and Gamble products (Gain and Cheer are two others) accounting for about two-thirds of the market.  Is Tide so good?  Does Tide really "know fabric best"?  I couldn’t name one supposed feature of the product and I’ve been buying detergent my whole life.  I couldn’t even tell you what brand I buy.  Maybe it is Tide.  This is the kind of question that Wikipedia isn’t much good for.