> Somewhere, that line exists where the company would financially benefit, I just wish they'd actually define it.

The line doesn't exists. It's most profitable for the company to repeatedly:

1. Have an ad-supported tier and a no-ads tier

2. Wait for most people to move to the no-ads tier

3. Introduce ads into the no-ads tier

4. Wait for people to get sick of ads

5. Introduce a new, higher cost no ads tier

There is no threshold where it's more profitable for the company to never introduce ads at that price point.