I also have heard that this is done. In habitat a lot of plants do grow in limestone areas, especially those from Puebla.
I have not tried this myself, although I did buy a bag of limestone chippings a while ago, but never got round to using it, mainly because I don't know how uch to use. The question of pH values has been debated a lot, and for a while I used to use a compost that was designed for lime hating plants as my basis, together with grit. But that seemed to have more peat or similar, and so I changed to ordinary John Innes which has some lime in it. I can't say I have seen any noticeable difference.
I went to Mexico in 2005, and especially in Puebla there was a lot of limestone. The plants, such as M. haageana, M. mystax, M. sphacelata, M. carnea, grew there in abundance. But always they had found a gap in the substrate, or grew in an area, where a fair amount of vegetable matter had collected. So there is a balance then between the natural acidity of decaying vegetable matter, and the water that has filtered through the limestone, although there would be some direct water from rain as well.
It is possible therefore that the natural acidity of the actual material in which the roots have gained a hold acts as a buffer to the alkali effect of the limestone fuelled water, in which case I'm not sure there's a lot of point in trying to mimic it.
If you use a slightly alkali potting mix, and water with slightly acid rainwater, I think you end up in a similar situation, without the need to add any additional limestone. And there are different form sof limestone, which seem to dissolve in slightly acid water at different rates, so unles syou really know what is happening, I think its best to leave well alone - so long as your plants are growing OK.