The performance was never the consideration for Nintendo. They want a handheld that can last a long time, so they will always clock their chips down. You can't compare 30 watts all the time to 30 watts plugged in, let alone 5 watts in handheld mode.
Steam Decks are great, but lets be real; when you play a big AAA title, even on moderate settings, you might get two hours out of the machine pushing it to the limit at full TDP.
This is kind of a nothingburger story. We always knew Nintendo were not going to scale their machines up to the level of PC gaming handhelds.