This feels like a classic Sonnet issue. From my experience, Opus or GPT-5-high are less likely to do the "narrow instruction following without making sensible wider decisions based on context" than Sonnet.
Yes and no, it's a fair criticism to some extent. Inasamuch as I would agree that different models of the same type have superficial differences.
However, I also think that models which focus on higher reasoning effort in general are better at taking into account the wider context and not missing obvious implications from instructions. Non-reasoning or low-reasoning models serve a purpose, but to suggest they are akin to different flavours misses what is actually quite an important distinction.
