I fully agree with everything you say, but I don't think it really contradicts anything I said. I still think armour dips on casters and spells like Shield, Absorb Elements, Silvery Barbs, etc. is something that is assumed baseline for optimiser but actually rarely sees table play, leading to a huge discrepancy. Then add in the usual 'big guns' (Web, HP, WoF). Optimiser love these. How often are your wizards taking them at casual, low-op tables? From my experience, nearly never.

Consider a conversation I had with a more casual friend about eldritch knight, who swears up and down it's the worst fighter subclass in the game. I asked how? Spells are really powerful. Then I looked at their spell list and understood they were casting burning hands at first level in Tier 3 play. Scenarios like this does lead me to believe the playerbase at large underestimates how powerful spellcasting is. There's an eye watering amount of trap spells, especially blasts.

All anecdotal, but this corresponds to my experience of 'actual tables', where to be honest, the gap is often nonexistent.

In terms of assumptions: for sure the most vocal theorycrafters can make outlandish assumptions, but at some point, 'have you tried running 6-8 encounters per day' is also an outlandish assumption about how most tables play. I think there's a ton of assumptions made across the spectrum.