Spell Totem Support level and Wither

I am reading this guide and can't understand small point about why Spell Totem should be leveled:

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Spell Totem - can be used in acts for bosses as well, but then you'll need an additional 3L: Spell Totem + Multiple Totems + Wither (everything except Spell Totem can be left at gem level 1)

https://pathofexile.fandom.com/wiki/Spell_Totem_Support

Spell totem leveling only increases Damage and Wither spell has no damage, so what's the point of leveling Spell Totem in this setup?

Level of Spell Totem support also raises the Summoned totem's Health. A lv20 Wither Spell Totem (20 is the Spell Totem support level) will be much healthier than a Lv1 Wither Spell Totem, despite all other support being lv1.

In the end of the day, this just means the totem won't die when the first white mob hits it, but will still get oneshotted at lv20 from Rare and Unique mobs, unless you invest in Totem Life (which, unless you are a Torchoak Chieftain Decoy Totem build or a RF Totem build, and you are not since you go Wither, you should never do on purpose)

Thanks, makes sense.

Wiki seams to be incomplete for some stats.

My lvl 1 totems indeed are oneshotted by white mobs right now.