Unless they have a strong internal technical team that understands the fit and benefit of suck stacks, most of these things are determined by third-party vendors\contractors. If you're beholden to contractors to maintain your services, you might be shy of picking something too new. Contractors can add a decent maintenance surcharge if they're maintaining something React\Angular based, for example, and its just not worth the risk.
By no means true for all everyone though. I've seen one or two different banks and superannuation providers pick up Angular for customer-facing financial calculators. There's certainly room to do the work broadly in industry if the fit is suitable.
The last few clients have all been startups who brought me in for specific projects due to lack of experience/hands/etc.