It's simpler to do one thing than to do two. You make a choice and you do that.
Could they be doing opaque ads right now and we wouldn't know? It's possible, that will probably eventually come to light and it might have legal consequences, but sure it's possible.
But it's not a given, and your logic of "it would make zero sense to leave money on the table" is certainly not a QED, it's absolute reductionism.
It's even simpler to do zero things than to do one thing, so we should expect them not to introduce any ads, right?
"Simplicity" isn't a relevant factor.
It sounds rational then to block as many non-opaque ads as possible, because that isn't their preferred choice.