I'm in agreement with most of what katemorrisviolin has written
Exams for an adult - just as they should
be for a child, are not there to be your sole musical diet. The exam syllabus is a syllabus, not a curriculum. There is lots lots lots more than just exam music out there to play and to learn.
Exams, for me, provide several things. A goal to work for is the most obvious. An insistence on things I might otherwise avoid is another - I would play only baroque music by choice, but list B insists on 20th century works. So I have to learn something modern and you know what, some of them are quite good
Don't tell anyone I said that, it would ruin my reputation
Technical stuff - scales, aural, etc - is very easy to avoid if you're not doing exams. Sometimes there is debate about how useful some of these skill are, other than for passing the exam. As I do TG exams, I don't have to sing in the aural tests, which is great for me - and the things that the TG aural does test are useful too. Perhaps identifying a cadence by ear doesn't sound that useful, but to identify one, you have to learn what a cadence is, what they do in the music, and then you find cadences all over the music you are playing and you understand what they do and how to deal with them.
Of course, if you don't want to do exams, then don't. Whether it's memorising scales, playing with an accompanist, a dislike of the syllabus repertoire, or playing in front of somebody you don't know, it doesn't matter what the reason is - they aren't compulsary.
The most important thing in my mind is enjoying
your music making. If exams are useful in your musical journey and you enjoy them (well, perhaps 'enjoy' is too strong a word, for those minutes of terror
) and can see/feel their benefits, go for it; if an exam is going to put you off music for life, then don't take one.
Graded exams are not the only option too.
There is the AB Performance Assessment, where you play some pieces of your choice to an examiner (no supporting tests), and get a written report (no pass or fail - and they will chat to you beforehand to see what you want to get out of it, what sort of thing you want commented on in the report)
LCM do Leisure Play exams, which are much like their grade exams but pieces only - no scales, aural, etc.