Not true. I have a HyperX moc and it’s always the default, no matter what app I use. I have several Apple headphones, works that way with all of them. macOS 14.7 now, it’s always been this way.
Never had a problem using my Sennheiser PCX 550 (Bluetooth) with a Rode Video Mic Go II (USB). But when connecting my AirPods MacOS would switch the mic to them.