McIntosh designs their integrateds for dedicated 2-channel systems only so they don't have HT bypass.
I doubt it. They sell a DVD player, right? It has 5.1 multi-channel output and video. Obviously they don't have an issue with HT/multi-channel or they wouldn't sell an HT source component.
It's rediculous to not provide an HT bypass. The whole point of an HT bypass/processor loop is to allow you to have a fine, dedicated 2-channel audio system and add multi-channel capabilities without affecting the 2-channel performance in any way. Heck, when listening to 2-channel music none of the HT components even need to be powered on in an integrated 2-channel/HT system which is connected through an HT bypass/processor loop.
The HT bypass/processor loop isn't really a necessity. It simply makes it a bit easier to calibrate your HT system. You can use any integrated amp (or pre-amp) and simply use any one of the unused line-level inputs for the amplification of your L&R fronts. The only thing the HT bypass does is provide a unity gain link that bypasses the volume control. If you have any specific questions on how to do this, let me know.
The proof is in the pudding. Find me a bypass switch on their integrateds and I will agree with you.
Also, I never said they don't do HT. Heck, they even make their own video projector!
However, it is true that all you need to do is rotate the volume control on the integrated to a unity gain setting (or some other if you prefer) and you can use your receiver volume control. A "bypass switch" is really just marketing jargon and isn't necessary, as Reubent says.