When I got my (admittedly car) license they made it clear that's illegal. Hasn't stopped people from doing it but yeah don't. Maybe get a quieter exhaust
Earplugs are pretty common on a motorcycle. The issue is not the exhaust, its the wind which gets to damaging levels at pretty low speeds.
Fully agree that its dumb but even on my electric motorcycle at sub-highway speeds, the wind noise was the only thing I could hear.
You're revealing that you have never rode a motorbike with your comment.
Riders need to use ear protection within the helmet unless they want to become deaf in the future, because of the wind noise.
It's illegal in a few places in the US, but not everywhere. It's definitely not illegal to put in a few kW of amplifiers and a few square feet of speakers, and often not even a problem to turn them all the way up and stop whole areas from hearing anything.