While it’s not an obvious choice for closeups, a supertelephoto lens can be surprisingly capable at macro photography. It’s not possible to get close enough for extreme macro photography of small bugs, but other wildlife such as butterflies or snakes are very well suited to this method of photography. In the middle of the summer I was walking around trying to find birds to photograph, and although I failed with that, there were many monarch butterflies around. While I didn’t have an extension tube, I was able to get close enough by using a 1.4x converter on my 600mm lens. An extension tube would have made it possible to get even closer, so I’ve now made a point of carrying an extension tube with me, because you never know what opportunities might present themselves.
There are several advantages to using a telephoto lens. Not only can you blur the background more than you could with a short macro lens (say 100mm), due to the focal length compression, but you you can shoot at wider apertures and benefit from a higher shutter speed. Whereas most macro lenses will be shot at f16 or narrower, to ensure enough depth of field when close to the subject, a telephoto could be used at around f8. Additionally, thanks to the extra working distance, you are less likely to scare off your subject. In this case I was 10-20 feet away from the butterflies, and this made it far easier to photograph without them leaving.