[norseman]

Time, Wicca is a pik-n-mix belief, with bits and pieces of many 19th century esoteric groups plus a smattering of Druidism and a religion grafted on from old fertility religions, all structured around a core of witchcraft.
Gardner was into everything going in western and eastern exotica plus the Celtic christian church [ he was an ordained priest !]. Making it an Initiatory faith was designed to give it an exclusivity to attract members. The concept of lineage often quoted is debatable in an organisation from the mid-1950's.

As time goes by, it becomes more popular in the US and less popular in the UK. The norm in the UK is self-declared Solitaries with no structured bureaucracy.
Where is seems to be of benefit is as an introduction to older beliefs, as it did for me. After 2 years, the lack of substance in Wicca led me into deeper paths.