Much like many disabilities, deafness isn't a hard binary between hearing Vs deaf, but a spectrum dependent on many factors. For example, someone may have hearing loss in a particular frequency range, which may affect their ability to hear lyrics. I would also expect that someone's relationship to music may be impacted by whether they were born deaf or acquired deafness later in life.
The point that other are making about this as an accessibility problem is that a lot of disability or anti-discrimination has provisions for rules or policies that are, in and of themselves, neutral, but affect disabled people (or other groups protected under equality legislation) to a greater degree than people without that trait. In the UK, for example, it might be considered "indirect discrimination".
You might not need lyrics to listen to music, but someone who is deaf or hard of hearing is likely going to experience and enjoy music differently to you, so it may well be necessary for them.