Good point from Brayden King and good point from Henry Farrell — all objections are withdrawn and I can now give a wholehearted endorsement. Either way, it’s a sign of how well-made the film is compared to most of what Hollywood turns out that a viewer can even clearly identify a theme and then worry whether or not the ending is really true to the theme. That’s why the fact that the film’s plot clearly has some holes winds up not detracting from the experience: There’s a point to the sequence of events so it’s not a problem that in a first-order way there’s no account of why things would happen like that. SPOILER.
This is most notable with Spiderman’s bouts of super-hero impotence which they don’t even attempt to make consistent with the origin story in any way. Why would that happens? Who knows? And more important: Why cares? It happens not only to drive the story, but to drive the theme that heroism is a choice at a higher level. You even see it in the scientifically absurd notion that you could “put out” a fusion reaction by dropping it in a river. Doctor Octopus sacrifices himself Samson-like to make it happen, and the occurence references his earlier, pre-villain thought that he belongs at the bottom of the river which, in turn, references Eliot’s line “I should have been a pair of ragged claws / Scuttling across the floors of silent seas.” The only threat is that just as the perfectly good Matrix story was wrecked by its two awful sequels, the two good Spiderman films will be undermined if they screw up part three.