What you don’t seem to understand is that the minimum focusing distance and the magnification rate are both independent of the camera body, they are part of the design of the lens, just like the maximum aperture is part of the lens design. SLR and DSLR bodies cannot alter any of those. In order to increase magnification beyond about 1:10, which almost all lenses will do, into the macro range up to 1:1, the lens has to be physically “moved†away from the sensor or film plane. Macro lenses do this internally by design and extension tubes accomplish the same thing by literally moving the entire lens further from the sensor or film plane. Point and shoot cameras can also do it because the lens is fixed in place and cannot be removed, so the camera can control the position of the lens elements. All of this disregards the use of diopters like the Canon 250D/500D or reversing a lens.
I went to a Pentax user forum and posted this question: “I read on a non-photography forum that this camera(*Ist DL) has a built-in macro mode that doesn't require a macro lens. Is this true?†The answer I got back was “No, that's not true. The camera has a macro mode but that just automatically adjusts shutter speed and aperture more fitting for macro. You still need a macro lens (or extension tubes).†It does exactly the same thing my Nikon D40 would do if I switched it to “macro.†That is not to say that it wasn’t adequate for whatever you were doing, it just means that it does not provide true macro capability without a macro lens.