This most likely is due to the fact that the main delivery method of RGB in home cinema (via Scart) is almost always non-progessive. When the RGB to YUV comparison is made, it usually consists of a progressive scan argument.
Component is just a way of compressing RGB to save bandwidth...it needs to be converted back into RGB for display (even on plasmas and LCDs via HDMI/DVI it is re-colorspaced into RGB, only in digital realm exclusively...since most content are stored in component form (Betacam SP, Digital Betacam, DVD etc) it is best to convert to RGB as late as possible, thus it IS marginally (but I'm not sure if obviously) better to send the signal in component form to the set because the only conversion was to analog but not to another colorspace...with SCART connection both D/A and colorspace conversions take place prior to sending the signal to TV...I have bought an Amstrad DVD player for both my woprk and my mum that sends progressive both through SCART and component (even has a VGA mode so you can build or buy a SCART to SubD adapter and connect progressively to your PC monitor...SCART is just a dumb lead, what happens at the source and receiving ends is what matters...I am only not sure whether prog scan TVs (CRT, Plasma, LCD) can take progressive via SCART but that is only a queston of implementation not inability...
here are the best solutions for connection:
Interlaced RGB DVD - Interlaced CRT = SCART RGB lead
Interlaced component/RGB DVD - Interlaced CRT = component lead (because the colorspace conversion happens latest in the chain - just prior to display)
Progressive scan DVD - Progressive scan CRT/Plasma/LCD = component lead (all progressive operations are performed in digital realm in component colorspace in the DVD player)
Progressive scan HDMI/DVI DVD - Plasma /LCD = HDMI/DVI (all digital, no D/A conversion, pure BLISS)
I stand corrected of course...