Well, they have limited themselves to single point of failure.
That's like selling only blue shoelaces and then crying faul when your only supplier stops making blue color.
If your livelihood depends on one account only, you are in great risk anyhow.
That sounds like anecdotal evidence. Android is more popular in more than half of the world and a lot of apps are successful and generate income on both platforms.
Pirate Party in Slovenia did not qualify for elections. They needed the support of 1.000 constituents, but when the officials did the count they only had 970 signatures.
What I'm saying is - your mileage my vary.
None of this account for differences in purchasing power and phone price.
If you have an $150 Android device, I would of course expect you to spend way less on software than somebody with a $1500 iPhone.
I'm not saying 'develop for Android only' but if your business relies on one ecosystem only, you're at a higher risk and you're leaving money on the table.