No, this indexing is a small way to contribute to family history and also to see a wide variety of source documents. The main activity in indexing is to enable documents to be searched electronically -- by capturing key data types. There are lots of indexing projects out there, looking for willing volunteer indexers. The one that I've dabbled in is facilitated by the Church of Latter Day Saints (LDS), otherwise known as the Mormons. They make their material freely available to anyone on the web.
I noticed recently, when looking for a new download from LDS, that they are working through the South African slave registers.
I know that a big UK project of slave registers was recently launched online (here), and I've done the inevitable and checked to see if anyone I know I'm related to was a slave-owner or a slave. My understanding is that when slavery was abolished in the British Caribbean and the Cape in 1833, slave-owners could claim compensation (from the state) for the loss of their "property" (their slaves). Through the archive of claims, one can see who owned slaves.
Working through a tiny sample of the South African slave registers is a jolting experience -- the phrasing ("these are to certify that the female slave X of Y place and Z age, the property of A, was on B date delivered of a C infant, since named D, signed A, Cape Town, date), the familiar names, the unpleasant surprise seeing my hometown as a place where slavery took place. This is despite what I knew about slavery in Cape Town already -- the Slave Lodge on Adderley Street, the stone marking the spot nearby where slaves were sold, the long history of slaves making their mark on South African history, some of them famous.
The documents make it real. Helping to make these records accessible feels both like a small gesture of respect for the slaves, condemned to only one name, and an acknowledgement of a crucial element of our polity.