Actually, the reason you buy a macro lens is so that you have a magnification of at least 1:1 at the minimum focusing distance AND if you decide to use extension tubes, the lens is already optimized for best quality at the minimum focus distance and closer.

The working distance on my Tamron 180mm is 18.5" and the Sigma is 15" - at their MFDs, the image magnification is 1:1.

There is no school of thought that if you use a lens at it's minimum focus distance AND your subject is fairly large, like a Hibiscus flower, there will be some cropping unless you move back. That's not an opinion.

At 1:1, it doesn't matter if you are at 6" from the subject with a 60mm lens or 18.5" from the subject with a 200mm lens - the amount of crop will be exactly the same because the magnification and the field of view will be exactly the same. But at 6" with a shorter lens you will encounter some challenges for lighting and lens /camera/human shadow.

The primary (but not the only) reason to get a longer macro lens is to have that 18" or more working distance and still have 1:1 magnification.

This is not a school of thought, it comes from applied practice.