Jquery is the old default for web apps from before people decided they wanted react.

What can it do that others cant? Literally nothing.

That didnt and does not stop it from being used for connivence sake.

The point is: if its not about the technical quality; why are we not still using it now?

If that is the point, then I feel it is made out of technical mediocrity, rather than excellence. A good team should be able to adapt the technology that best fits the task, and companies should be able to hire for it. Or stay mediocre otherwise.

The hiring issue is home made. If companies started hiring for engineering skills, rather than familiarity with existing tech stack, it would change quickly. Experienced engineers are able to learn new languages and frameworks on the job. Of course, if hiring is too petty to give engineers a month of getting familiar with the product and expect readiness from the get go, then they will continue to miss out on talent.