Doesnt really apply to Sanji
Sanji had a way stronger focus on his character writing post-ts than pre-ts, and this includes post-nika arc like Egghead. Dont know about the lesser strawhats they seem to suffer that's true. You are free to compare. Like if Skypia happened today for example people would say sanji had no solo fight here and meme that enel one shot him (which was a legit one shot, not even a agenda meme), that would be it. Overall nothing character critical really happened to Sanji in Skypia, he had some cool pages but the same as always. You compare that to egghead where Sanji is the only one grappling with Vegapunk situation, the one directing the crew through the arc with orders, trying to hold I together and so on.
And he is way more tied to the main plot parts than ever, he learned about Nika and Seraphim from Vegapunk, knows about the magic circle powers of the Gorosei as he saw it twice, encountered Kizaru, was present when Saturn was talking about bonney and her mother, was present during Vegapunks final wish to die, talked with the giants and even directed them and so on