These days it seems as though everything is digital but in the backpacking world cash is still king. Therefore, if you are wandering around whatever place you happen to be in with a wallet full of cards you are just asking for trouble.
Everything in the United States is driven by credit cards. This might be because you are trying to rack up points or miles on a card or because rumor has it that some places will not even accept cash anymore. Personally, if a place i frequented started to not accept cash I would stop frequenting that place because I don't like being tracked and that is exactly what cards do to you.
The reason why you don't need to carry all of your cards with you whilst backpacking is pretty simple really: Most places don't have the machines to accept them anyway and if you lose or get your wallet stolen you are seriously fucked.
I, just like most people, have a number of cards. I almost never carry them with me when I am traveling and especially not when i am simply wandering around a new city that I am not a citizen of.
I'll never forget the day that I met this guy that I refer to as an "asshat" and I'll just call him "Kevin" because that was his name. I met Kevin at a bar in Bogota and he was a pretty cool dude but obviously wanted people to like him by virtue of how much money he had. He wasn't terribly old and he certainly wasn't a playboy. He was overweight and dressed like someone that probably makes close to 6 figures but not quite.
If basically anyone came into the bar he would immediately offer to buy them a drink which is a nice gesture and I have to admit that we all had a great time while we were around him even though at many points we told Kevin to stop buying rounds because it was getting a bit silly even though the drinks were really cheap where we were.
We were having fun and Kevin was ignoring our requests to stop getting more rounds on his bill even though at one point I actually had a queue of 3 beers including the one in my hand. I will say this about Kevin: He was a nice guy but seriously, that guy has a drinking problem.
But he had a much bigger problem than alcohol and I think it was intentional. Kevin would leave his wallet, which was overflowing with cash and about a dozen cards just sitting on the table where we were and we were at an outside table. At times, Kevin would leave to go to the bathroom and just leave his wallet there. When I was around I would put my hand on top of it to protect it because I think I am much more aware of the nature of society in Colombia or just globally speaking than he was.
I think this is kind of a foregone conclusion at this point, but at some point in the night Kevin's wallet went missing and none of us took it. It's just a question of him being a jagoff and someone on the street noticing this. To this day Kevin (who I still keep in touch with) has no idea what happened to his wallet but we presume it was simply picked up by someone who was passing by.
Here's the thing about Kevin who even though he is my friend I still consider to be a class-A douchebag: The cash that was in his wallet was rather meaningless to him - he was and is very wealthy. However, the 12 or so cards that were in his wallet posed a much bigger danger than the cash that was in it and even though he was (and still is) and arrogant asshole he was worried about what could be done with those. It's not like small shops in Colombia that accept credit cards are going to check ID or anything.
By the time Kevin finally got all of his cards cancelled it was DAYS later and thousands of dollars worth of purchases had been made on his cards. I don't think that he was financially liable for this but the fact remains that this guy, who is a douchebag but otherwise a very nice and generous person, had to spend DAYS on the phone with credit card companies to sort his situation out.
I think I can presume that most people out there are not like Kevin. Kevin is a one-of-a-kind jagoff but a loveable one at that. But if you are carrying a bunch of cards which can't even be used in most places you need to take a look at yourself and ask "why am I carrying this plastic crap?"
In the end, you are only creating problems for yourself if you do carry a bunch of cards around and honestly, it is much better if you just leave them in the safe-deposit box back at your hotel.