> How would you know? You are choosing conventions over measures.

Because I worked in the industry when we all used jquery and I see the difference in real billable hours to nowadays. The entire industry has measured and shifted. Do you think million- and billion dollar companys shifted towards public shared framework for funsies and parties?

No. I don't have to hire an engineer and teach him our company bespoke framework. I can hire a react developer and he's productive from week one.