Do painted block pools need render?

[Fubar]

If my understanding is correct, a painted (Chlorinated Rubber) pool gets its waterproofing from the paint, not the underlying substrate.

In that case, hypothetically (aesthetics aside), is there any reason a waterproof render is NEEDED before painting if using flush pointed concrete block construction?

The only reason I can see is that it stops ground water ingression under the paint and causing delamination.

I await more knowledgable people than I

Cheers