I completely agree. I just think that we're seeing a category of developers that consider the front-end to be of higher priority, with everything that goes with that mindset.
Absolutely. Performance on the server costs money. Data breaches cost money. I'm sure someone can quantify whether using a jQuery plugin instead of a React component has a cost associated with it, but I'd venture to say it's on a magnitude of order less than server-side concerns. I don't know that I'd say priority should be 100:1, but at least 10:1.
Very business dependent, but typically speaking the brunt of development effort (for tech businesses) is going to be on the backend in terms of man hours. In some orgs it's like 100:1 backend:frontend (or more?).
You certainly may be right about the ratio, but I think that this factor and the degree of importance are not mutually exclusive. At my last employer, this ratio was certainly present, and resulted in a sinful front-end implementation. The front-end was very important for customer experience (resulting in sales) but by the time management realized this, it was a massively arduous process to iterate on. Since server-side development was highly prioritized for a very long time, the two couldn't grow together, resulting in off the shelf solutions cobbled together with java server rendered static pages.