I’d long been using my Dropbox basic with more than 3 devices and never had any problems. That was until I configured a new system and got a email to inform me that I cannot add any more as it has a 3 device limit.
The only annoying thing I find is that this limit clearly never existed, because I had long exceeded it with no problems. Suddenly its enabled and forced with no advance warning. Really a good way to annoy people by having no advance notice.