This information comes from GamesBeat who has heard from their sources that the Switch is less powerful than the 3-year old PS4. Their source claims that this is because the NVIDIA chipset used by the Switch is based on older Maxwell architecture instead of the newer Pascal technology. This means that you can pretty much cross off 4K gaming on your wishlist.
However there are some questions about this claim, such as if it is based on older technology, how does it run Skyrim? Presumably the copy of Skyrim we saw was the remastered version with updated graphics which means that its requirements is certainly different from the original, unless Bethesda created a scaled-down version of the game just for the Switch.
In any case take it with a grain of salt for now, but it’s the same case with Apple’s iPhone where many question its choice of RAM and processor. However if you’re fine playing Nintendo’s games that don’t necessary have the best graphics or best resolution, then we guess maybe this won’t be too much of an issue.