Since I don’t use the Tablo to watch LiveTV and all my content is extracted to my Plex Server I don’t need the Internet for my Tablo except to get the Guide data updated on a regular basis. My device ran just fine for 2 days with no Internet while I was updating routers, switches and WiFi last month. Wifey still enjoyed her shows and such without interruption.
Again, a static IP is just personal preference and a choice. Most IT admins that have been in the game for a long time just have preferences and prefer things certain ways.
Also it doesn’t prove anything and it’s not useless. It’s just a preference, one that we have no choice about using the Tablo.