It sounds personal for you.
React is more popular than Ember.js will ever be.
However this is apples to oranges, one is a view library, the other one is a batteries included framework.
I think you're a little out of touch if you honestly believe Ember and especially Ruby on Rails are legacy products. We have multibillion tech companies shipping 10+ years old existing apps and building new apps in both of these frameworks.
This mindset of branding stuff "legacy" because it's not trendy on Twitter or reddit is one of many reasons why JavaScript fatigue exists.
All while Ruby on Rails developers are one of the most happiest and productive web developers shipping stuff because they don't need to reinvent the wheel and solve problems that have been solved a decade ago. (p.s. I've never done RoR, I just understand what convention over configuration does to developer productivity)
If you want recent examples, go look at Apple TV web[1] built in Ember (even though I personally wouldn't use Ember for such a project) or Hashicorp building all their products in Ember and releasing their new Helios design system[2] in Ember just few months ago.
Again, these examples don't matter.
I've hired full-stack JavaScript developers, I couldn't care less if they've done React, Ember, Angular, Vue, Svelte or whatnot.
Because it'll take any proficient JavaScript developer a week or two to understand the concepts and structure of any framework or library above. They all do the same thing - render pages and wire up buttons to run network requests, I don't understand why people make it sound knowing React, Vue or Ember is equivalent to knowing C++.
It's all JavaScript doing the same thing slightly differently.
> What has Ember done but continually play catch up for years and years on end?
You can find your answer here https://www.intercom.com/blog/evolution-of-ember-at-intercom....
> How many years do you have to scroll back to find anything that influenced anything outside of Ember?
I can tell you about ember-fastboot, ember-engines, miragejs, glimmer vm, i18n, accessibility and other things Ember and Ember community have done to SPAs in the last 15 years, but again, why does it matter right now?
Stop measuring who's done more. There's nothing I can tell you that will change your mind, just enjoy whatever you use now.
All the best <3
[2] https://www.hashicorp.com/blog/introducing-helios-hashicorp-...