Yes, absolutely can have a lot to do with mud, gunk, dust, sludge in the works. A clean chain is a happy chain.

I clean the entire bike including power train (chain, deraileurs etc) about every 3 rides, or 300 miles, or whenever the bike "asks" me to, whichever is first.

I've got 4 minutes left on break but we've got a lot of new bikergals here so there's tons of info re maintenance here.