Not playing games at all. Just showcasing the facts as they present themselves in the natural world.
Of course both components is critical. Having a gaping hole at one end of the floor is general as losing proposition. No one would argue otherwise. So yes, the question is then, which is more important.
Very simply Looking throughout history at sports, it's hard to come up with primarily offensive teams that have won it all. It's pretty easy to find primarily defense oriented teams.
Again, using the article somebody posted above about the Top 5 defenses ever:
1985 Bears
2000 Ravens
2015 Broncos
2013 Seahawks
1986 Giants
Every single one of them won the Superbowl.
And in my opinion 4 of the top 5 (or so) best offenses ever:
2013 Broncos
2016 Atlanta
2007 Patriots
2001 Rams
None of them won the Superbowl.
The best defense usually cancels out the best offense, year in, year out.