Not a hope. They may not give you the Plague, but you're here forever nevertheless and they own your soul.

Case in point: after four years of alternating between the Midsummer / Xmas parties, it was brought to my attention (by HR, no less) that it had been noted I wasn't attending both ̶m̶a̶n̶d̶a̶t̶o̶r̶y̶ optional gettogethers each year.

Avoiding the optional social events is unmutual of you and will be held against you. If you want to get ahead in your career, have a family, but live (separately) in a hotel around the corner from the Office and, instead of spending Xmas with them, go to the corporate event.