What you said is more applicable to gym memberships or cell phone contracts where you actually sign in-person multi-page agreement for 1-2 years conscious slavery.
CC chargebacks works just fine for any online business that try to pull a quick one on you and making it artificially hard to cancel/unsubscribe/change services.
Most people choose to spend 1-2 hours online try to get hold of someone "who can solve your problem". You CC service dept can do it faster for you by transferring the problem to the other side.
I mean - it's always fair to try to solve problem by contracting vendor to have them to honor your legitimate request first. If that doesn't help [quickly and painlessly enough] - then there is a plan B in place.
I'm not familiar, but this seems unlikely to happen for something as small as a Dropbox bill. Debt collection is a 'regular' business - it's simply uneconomical for a business to pay people to pursue your $9 Dropbox debt.
