I've been in the market for 30 years, had some of the best jobs on earth doing FE, and only did my first React project last year. Maybe I'm an anomaly but I never felt that not knowing React has been a problem. "table stakes" is too strong a phrase.
To be fair, "30 years of experience" likely opens more doors than any particular skill listed on your CV - that doesn't reflect the way that a majority of junior/mid-level devs need to present their abilities, where pattern-matching is an unfortunate norm, particularly when there are orders of magnitude more applicants than open roles.
Everywhere I've worked would have judged heavy emphasis on framework expertise rather than fundamental CS concepts and web standards as a red flag. I don't think it's that rare.
Mentioning ability in React is obviously not a bad thing but some people make it their whole resume.
Counterargument: my colleague with 15y exp (10 C++ & 5 Angular/Vue) has been unemployed for 2yrs already because he has no React on the CV and no local company wants to hire him (secondary size tech hub in the country, EU). He's probably have to force-relocate soon.
