Home audio is 8Ohm, Generally car audio speakers are 4Ohm, I don't know where you guys got the idea it's 2Ohm.
Some subs, in particular dual voice coils, are 2ohm so can be wired in series to make 4 Ohm or wired parallel to make 1Ohm.
There are benefits and drawbacks for each, lower Ohmage draws more power output from the amplifier if the amp is capable of running lower ohmage. The downside is sound quality is reduced. Some would say that is not so crucial at lower frequencies BUT I certainly wouldn't be going less than 4ohm on your component ( front) speakers.