for some openings, the 'paths' do not really matter. You might have 25 transpositions leading up to the same position after 10 moves. A well known example is th

for some openings, the 'paths' do not really matter. You might have 25 transpositions leading up to the same position after 10 moves. A well known example is the classic isolated d4 pawn position that might come from: - Nimzo Indian - Caro-Kann Panov - QGD - Slav - c3 Sicilian - Alekhine's defence and others. Popularity has not a lot to do with the openings themselves but with other things like a good book being published, or a popular match (like WC). Another thing you have is that some variations are really popular, and have good results, but are at one point refuted by a single game. As a result of this, the variation dies. but remains to have very good statistics.