If you think about it, argument over fairly inconsequential things is more valid than about the “big” topics, since a person is far more likely to have their mind changed. Take religion: no one has ever had a religious conviction changed through argument. Religious argument is about reinforcing one’s own belief system, not about convincing others. Politics? It’s just an excuse to get on a soap box to air out one’s own ideas against an active opponent. We could argue about religion or politics until the end of time and not change a fucking thing. You either have to let it slide or beat the other side into submission. Agree to disagree, or fight, to paraphrase Ian M. Banks.
And besides, argument as a whole really isn’t about convincing anyone about anything. It’s about having fun with a mental exercise. Some people play chess, others do crosswords, lots like to argue. And it’s the people who realize that argument is as meaningless as any other pastime that are the best at it. So really, the topic is completely irrelevant, so long as everyone involved is into it and is either reasonably informed or a good bullshit artist.