Cameras and GoPros are not Android Phones. SD Cards are great for PC's, cameras, media players, etc. They definitely can be useful on Android Phones, but so far the implementations have been wildly inconsistent across OEM's and across software versions within the same OEM. Most cameras, GoPro, media servers, etc. do not have access to sensitive information about the consumer and so the security risks, if any, are very minimal.
The security issues on an Android phone or tablet have to do with the read/write permissions that apps must be given in order to access that content and how it is related to internal storage versus external. Google attempted to resolve that by creating an adoptable storage option, but most OEM's are eschewing it entirely and for those that do use it... it leaves things to be desired. So in either case, having one giant block of storage is a better solution than having two types of storage being pushed together and even more so if that pushing together is two different formats that play by differing rules and have different security protocols.
Again, the security hurdles are the biggest reason that Google doesn't want SD cards, with the performance and stability issues as secondary reasons. Any number of cards failing or not failing, isn't the point - the thousands of threads were brought up to highlight that they do fail, and they fail a lot. That was a counter to the anecdotal "I've never had one fail" argument. SD cards do fail and they fail at a much higher rate that internal storage.
They also vary on speed and we all know that not all consumers are paying for the best cards available. It is my opinion that Android should do a speed check on the card when it is first inserted and if it doesn't meet a minimum threshold, not allow it to be utilized for anything. But even easier than that, is simply providing sufficient internal storage and not worrying about it at all.