There are a lot of myths being brought to the front here.
The OP's aluminum frame was anodized based on a corrosion concern. It is known that aluminum alloys, especially the more exotic versions, are prone to corrosion and with it crevasse cracking. Aluminum or any metallic has the known property to build in stresses at any cross section change of the material. Also, all metallics can fatigue and fail. This is the proverbial beer can that is bent so many times until it fails. In these cases, known limits of elasticity are exceeded.
As for composites and in particular carbon based materials that are commonly used. Fatigue does not occur to the fibres. Carbon structure failures would happen in two formats. First is an adhesion failure, second is the explosive or catastrophic failure wherein the epoxies have no adhesion failure, but the carbon fibres are pushed beyond limits and fail violently.
To classify carbon superior on account of not having a frame fail is not a good statement either...it simply means that it is overbuilt, however the mode of failure when comparing metals to composites forces the designer to not even consider the implication of the carbon failure. In essence it would be ugly.
As for UV, that is a concern of the resin system. Depending upon the final use of the carbon fibres, in general terms, this determines the base material the fibres are made from and / or how many fibres are bundled together for processing. Aerospace fiber bundles are typically made from PAN, while other industry fibers can also be made from PAN, or other base materials, such as tar pitch or Rayon, may be utilized. Regardless of the process and base material, all fibres are produced at extremely high temps in a controlled environment. The idea of UV affecting carbon fibres is the equivalent of UV affecting the remnants of a campfire.
There is a lot more to the which is the best than what supports you fanny down the road.