My understanding is that with vinyl, if the signal has too high of an RMS at low frequencies the needle can literally skip off the groove, and for this reason vinyl can't necessarily be as compressed and loud..
• The audio is subjected to low-pass or all-pass
filtering, which can result in broad peaks becoming
slanted ramps.
• The amount and stereo separation of deep bass content
is reduced for vinyl, to keep the stylus from being
thrown out of the groove.
http://www.laweekly.com/music/why-cds-may-actually-sound-bet...
Hence the RIAA curve, which is an eq curve applied to the mastering before put to vinyl that reduces the lows and exaggerates the highs. It is reversed by the phono preamp during playback.