No, it's not simply about worn records, but also records when new.

This is the title of a long thread in rec.audio.pro that started
in 2011, that I've just discovered by chance. Many responses
are technical in nature, but I thought some members here might
be interested?

https://groups.google.com/g/rec.audio.pro/c/W9NIGSpo1a0

fwiw, the latest response to the thread is:

"They were often pressed on polystyrene, not vinyl, with the
accompanying surface noise problems and were usually played on
decks with a heavy arm using cartridges with limited compliance.
As a result, they got damaged on the first play, and "as new
condition" on eBay as often as not just means no visible scratches.

Many of them were also over modulated, and very few cartridges can
manage to play them cleanly. Think 128kbps MP3 as the best quality
most of us ever heard from them."

HERE IS ANOTHER DISCUSSION OF THE TOPIC:

What Causes Most Distortion Heard on vinyl 45rpm Singles? https://forums.stevehoffman.tv/threads/what-causes-most-distortion-heard-on-vinyl-45rpm-singles.1091108/

A search in Google will reveal many other discussions relating to
45s and LPs quality of sound issues, notably in Reddit, Quora and at https://www.vinylengine.com

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