Witness funding was and is not intended to fund projects after it was cut 80% (I believe in HF12).

Some witnesses do get involved with projects as part of their campaign for votes, and given surplus funds under some conditions, but that's not a core part of witness rewards based on how the budget was designed.

By contrast, witness rewards were intended to support projects prior to being cut 80%. That bundling was not seen as a good approach and was a good part of the motivation for the huge 80% cut. It was always envisioned that: a) existing reward funds could be used to fund projects via voting for posts, and b) something like SPS could be implemented later to more directly fund projects without the somewhat messy process of doing it with posts. It took almost three years to get there, but better late than never.