Because of its notorious fight against a Tyrannosaurus rex in back in JP III, it seems that pretty much every time a Spino shows up somewhere in media, it is required to have a confrontation with a T. rex.

People often say that they dislike the Tyrannosaurus vs Spinosaurus fight is bad because it disrespects T. rex. I disagree.

I think it disrespects the Spinosaurus more.

The Spinosaurus in JP3 was already a very unique and new threat. It has a slimmer snout, allowing it to reach into smaller crevices, like in the plane and fence attacks. It has big arms that it uses a lot to roll the plane over and stuff like that. It can swim. It's already a great threat in its own right.

The T. rex fight disrespects the Spinosaurus because it shows that the filmmakers didn't trust that the Spinosaurus would be perceived as a big enough threat on its own, so they had it beat up a T. rex so it would look cooler.

Spinosaurus was already cool. It didn't need to beat up a T. rex to be cool.

Additionally, even if the Spinosaurus wasn't already cool, the fight wouldn't have really been that effective at making it look cool. Prior to this fight, all the JP T. rex had fought was a single tiny Velociraptor. Beating up the T. rex really just doesn't tell the audience anything about the Spinosaurus.

The humans aren't gonna engage in combat with the Spinosaurus, anyway, so what does it matter that it's a better fighter?

The Spinosaurus is a really great addition to the franchise for most of the movie, but this is its worst scene by far. It reduces a really unique animal and a really unique threat to just being T. rex 2.0.