Some people are not as logical in their thinking as others. Some people are also simply more technically challenged than others. No big deal, although sometimes those who are technically wrong seem to make the most noise
To have minimum audio sync issues without any additional correction, run HDMI (or component/analog) directly from source (like DVD player) to TV and use the TV's speakers. You lose the multichannel capability, of course. A modern TV, like the Samsung 7 series, knows the specific amount of delay in the video path and can properly compensate for that in the audio path to synchronize audio with video. With AMP on, there is typically a 1.5 to 2 frame delay in the video (60 Hz frames). You can also run the digital optical out of the TV to the audio receiver, since the latter typically has very little audio delay, but you get a downsampled stereo audio output instead of multi-channel.
If you run the HDMI to the receiver and have it deliver the video to the TV, you are subject to audio synch issues, because the AVR does not know how much delay there is in the video path. Here is where the lip sync adjustment comes in: the AVR can add in additional delay to accommodate the delay in the TV. If you run the HDMI from the source (DVD player, e.g.) to the TV and then digital audio (optical or coax) to the receiver, there is also a possible lip synch issue because of the larger delay in the video path. So the advantage of using the AVR is the potential to adjust lip synch, although some DVD players actually allow variable delays to be set. But you don't need to send HDMI to the AVR in order to use the lip sync adjustment feature: you can just send digital audio and use that feature. Remember also that the amount of video delay in the TV is a function of mode settings on the TV, so the same lip sync setting in the AVR or in the source may not work with all TV settings.
It is simply incorrect to say that using an AVR to split video from audio will not cause lip sync. It could, because the AVR does not know how much video delay there is. It may make a guess, but video delays vary among TV's, and can also vary as a function of inputs and settings on a given TV.
By the way, if you use a HTPC, lip sync issues can be taken out by settings in the media player. For example, the very capable Media Player Classic has an extremely wide audio delay adjustment range, so it is perfectly fine to send HDMI/DVI from PC to TV, and audio (via S/PDIF) to receiver. Absolutely no need to send HDMI to receiver.