The Shield That Guards The Realm of Men
I don't deny that growth, but neither Obitos over time
No proof Obito grew over time though
Dude was pretty much fully grown by the time he fought Minato and not once is it implied the dude got stronger since then (apart from gaining the Rinnegan or the Juubi ofc). There is actual proof the Sannin got stronger by developing new techniques or acquiring forms.
The most you can argue is that he can use Izanagi safely (Madara already had spare Sharingan so even this is debatable).