This just isn’t true. React has been going strong for 4 years with no sign of slowing down.
Reference: https://youtu.be/-HUHRRYQl5k?t=2m4s
However, mobile.twitter.com and facebook proper are using react. Along with Walmart.com and many, many others.
The biggest Angular app I've seen is probably grubhub, and there's some painful state bugs there... in fact I don't think I've ever seen an angular app (not using rxjs or redux) that doesn't have weird state management bugs.