>maybe low radar cross-section isn’t that big of a deal anymore

That's simply not true. There is not a peer or near-peer country that is not developing a variety of low-RCS aircraft.

Your target is long gone by the time you can detect short wavelength visible spectrum. Jets don’t need to get physical with you to do damage, it’s not WW2 anymore. That’s not to say countermeasures aren’t a focal point of research.

There are lots of “smart people” out there shitting on very serious work after reading some tweets from captain obvious. There are lots of even smarter people who don’t think everyone else’s an idiot and therefore think long and hard before shitting on work they don’t understand.