Phaser cannot do 3D games well.

Also, the Unity Asset store has so many great assets for me to use.

And 3D tools like PlayCanvas are browser based for their editor too. Desktop apps still have a massive edge in productivity.

Unity has Timeline, Cinemachine, Particle System editors which make detailed tasks possible.

Unity takes care of format shifting your assets into a compatible format, saving oodles of time.

And C# is a superior language to Javascript (never use == use ===). Visual Studio a better IDE than debug in browser