Solid point, I think there are times were the difference between a planeswalker and a creature are relevant, but I think the dack comparison is most apt. I can imagine it being relevant in something like RUG or BRUG planeswalkers depending on your meta, but Dack seems like it will generally be better.
+1 to using a rental service. I think 500 tix rental capacity on cardhoarder is like $15/week, which is sort of expensive but takes about half a year to catch up in price, and also let's you change up decks as much as you want. I have gone back and forth in terms of MTGO. I think ultimately i like the interface better than arena, even though it is a little clunky. It feels like it has all the nuances of "real" magic to me. You will lose games to the interface for the first couple weeks though. It sucks but it is real.
Oko can make 3/3s under humility for the same reason mishra's factory activated with humilty out is a 2/2. Both abilities are setting power and toughness, so what matters is time stamps. If humility is out and I +1 oko, the result is a 3/3 because the timestamp of that ability is later.
Oko is already winning most creature fights at a lower mana cost. Maybe Humility adds some percentage to that, but it is also a 4 mana card that isn't super impactful against several archetypes. I just don't see it being worth the deck slot.
@desolutionist and I just played a set of matches that were lots of fun the 4x Tinker, PO, Vault, Key deck beat xerox but definitely got a bit lucky. And then gush tendrils lost to xerox. Fun was had, this reminds me of vintage in 2014/15. I haven't tried to play against shops yet though. Overall the format is explosive but not like actually that much more insane than some of the versions of the format I actually played in.