Except in the US where they tend to get ignored.
Ever since DVD was launched in Australia, there have been people who will mod a player or who will sell you a modded player. Pioneer were even selling region-switching players from the factory until the DVD Consortium said they really shouldn't do that.
The hardware makers want region codes to Go Away because it is an additional complication in building their machines. The end-users outside the US want them to Go Away for exactly the reason you did: so they can buy and watch DVDs from another region.
The content owners and distributors want region mods to Go Away. Only if they get rid of regions will region mods go away.
Wade.
BTW: region 6 is China, IIRC. I don't think that's what he meant. Most region defeating hardware will try to guess what the DVD wants and set itself accordingly. If it can't figure it out (which is very rare), it leaves it unchanged. The effect is that to watch a region-difficult DVD, you put in one of the same region first.