Evan,

Remember: we are primarily working for what works easily and practically for home pool owners.

What problem do acid and base demand tests address than cannot be easily dealt with without them? And are those particular problems common or highly unlikely?

If my pH is high I can use a gradualist approach of adding Muriatic Acid to bring it down.

If my pH is low I can use a similar approach by adding Borax to raise it.

How much easier do those tests make these tasks?

If a pool owner can handle all of his/her issues both when the pool is clear and when there is a problem, without acid and base demand tests, then they are NOT particularly useful for that pool owner. That's simple logic.

Not every tool is necessary for a home-owner.

Carl