[int_19h]

Except they are used today. Russian 5.45 is famously highly prone to tumbling due to its design with bubble of air in the front of the bullet (even more so than rifle rounds in general). If we look at American 5.56mm, the original M193 was prone to fragmenting, which the original study reports on what would eventually become M16 noted as the reason why it's capable of creating more devastating wounds then the then-standard M80 ball. And modern M855A1 fragments even more reliably (at lower velocities) while still punching through armor.

Pretty much any OTM round is effectively expanding and/or fragmenting (depending on velocity) as well...

So for all practical purposes this convention hasn't been followed for literally decades now. The pretense is that we claim that all these bullet designs just happen to do what they do. Although IIRC the US military authorized use of 9mm JHP in some circumstances, as well, so I think even that veneer is mostly gone by now.