If you sing or play a brass instrument, the loud booming that comes from inside your head and reflects against plugs (or your fingers), called occlusion, makes traditional plugs unusable or actively harmful. The only solutions are to use custom molded plugs that go past the bend in your ear canal ($$$) or over-ear defenders which do not have a neutral reduction in sound across the spectrum.

In my experience this shape gets uncomfortable quickly because it’s jammed deep into people’s ear canals without accounting for the unique shape of each individual’s canal, so there can be a lot of uncomfortable pressure and friction. Ear buds tend to not go deep into the canal and rest closer to the entrance, making them sustain longer before discomfort arises in the ear.

Also this form factor doesn’t attenuate all frequencies evenly, which can make listening to music less enjoyable.