I know Nintendo includes this step in their hole-punching troubleshooting guide, but it's just not necessary. I've never met anybody who needed to do this to get their NAT traversal working, it's worked out of the box for every Switch game I've used for everybody I know. I'm sure there are people with weird or bizarre enough networks that standard STUN techniques don't work, but in my ~4 years of playing switch online games with my friends I've never met any of them.