I'm afraid some of us are illiterate when it comes to written music, countess. It's a shame and all that, but it's a fact.

The other side of that is there are people who can sight read, and can play excellently, but they freeze rigid at the very thought of playing without a score in front of them. You often get that with young people who don't yet appreciate what they can actually do if they jump in the deep end.

It happens with print as well, with people who don't trust themselves to sing without the words in front of them. Though that's more with older people who don't trust the old memory.
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For most people the chords request for simple tunes is just a stage in building confidence. When it's a question of trying to find the chords played by a particular performer, or in a particular arrangement, it's a different matter - as Simon G for one pointed out, there are lots of different chords you could play for any note, let alone in the course of a tune. It's not hard getting chords that would fit generally - but finding the ones used in a particular setting is not that easy.