What is the correlation between socializing and career development?

It is often said that one should develop a good rapport with his boss, and extend the boss-surbodinate relationship from the workplace to visiting your boss occassionaly, attending parties and clubbing.
Some even went as far as constituiting a group or call it cabal, they decide who to be promoted at club house, golf course and other social gathering.
No matter how good you are on the job, if you do not socialise with them or the powers that be... Your career growth will be stunted.

I hate partying, same goes for clubbing and the likes and is affecting my career.

Why are there so many unfavorable condition attached to career growth?