Physics doesn't prevent reproduction of bass in IEMs. Thanks to inverse square scaling of sound pressure with distance, putting the driver within the ear canal greatly reduces the required output level to the point where even tiny drivers can handle it. Lots of IEMs can reproduce loud, deep bass with low distortion.

You of course miss the whole-body tactile vibration effect of loud bass played on speakers, but the sound itself is there.

There is no such thing as over the ear monitoring. There good headphones like HD600. It has good mids and great highs, however the base rolls off towards 20hz. Many AirPods, include AirPod Pro 2 have better low end than what people use for monitoring, which is what, by the way? I play electric guitar, and use different types of audio equipment, and I really wouldn’t care if I use BD DT770 for tracking, despite the fact that it has absolute terribly inaccurate response curve. Just because they call it “studio” on the box, doesn’t mean that it’s the pinnacle of audio fidelity. There are many IEMs, including Bluetooth ones that are better for listening to music for music sake, as opposed to trying to hear some exaggerated spikes in 8khz.

Given that the highly vague cliche reference of your comments, this conversation is probably concluded, all the best.

To all other readers, please enjoy your IEMs and TWS but make sure they have an EQ and try to turn down the boomy base and piercing highs of some manufacturers like Bose and Sony.