And that causation is very often worked out by the GM making reference to notes/ideas that were/are hidden from the players.It is just that in trad approach the bad thing is usually assumed to be causally related to the action you took
This is part of @Campbell's reply to you: this sort of approach does not actively support player-driven, thematic and protagonistic RPGing. It encourages play based around discovering, and/or hedging against, and or working out the consequences of, GM's secret info.
The question asked was,For contrast, in 5e
Player chooses going in that they'll power attack, meaning that they will also not be able to avail of a shield.Player rolls to see if they succeedIf they succeed, they roll again to decide if they inflict full or some lesser quantum of damageI don't think any of the above necessitates GM splicing: the meaningful difference is on what happens on a miss. In 5e combat, the price in tempo is deemed sufficient. Tempo, strictly speaking, isn't available as a systematic cost in AW. For 5e broader abilities, the DMG version of play is that GM must have in mind a meaningful cost for failure. In this narrow case, the absence of GM moves is distinctive.
And here we see the answer. The system does tell us what content the GM can introduce, when, and how. And different systems foreground different sorts of stuff. Where in the example of 5e resolution do we see the player's thematic concerns being foregrounded? They're absent, for the good reason that having regard to them is simply not a factor in 5e's approach to resolving declared actions.Why it is ill suited for it? It seems to be almost completely about what criteria the GM uses whilst framing content, and that seems rather system independent.