Don't start making up numbers when it comes to 32 bit max memory supported. 1GB is assuming he has a 1GB video card. You can use 4GB total with 32 bit, including your graphics card memory. So if your graphics card uses 512MB of memory you can use up to 3.5GB regular RAM.
Maybe it's because they have had 0 credibility since they sold their site. What's hilarious is that a lot of people think they're still a legitimate source for hardware information.
http://scientiasblog.blogspot.com/2006/09/toms-hardware-guide-sells-its-soul.html
Good hardware sites...
I've never seen Metro 2033 use over 1.5GB of RAM.
As for Crysis 2 and Battlefield 3, neither are out and I would be very surprised if they use over 2GB of RAM.