Thats true but its still the item what was instructed in the tutorial to make and use.You repeat this over and over again but it is not true. They are not tutorial tools. They are regular tools and useful.
Some people keep the stone axe for a long time because it is a universal tool that can be used as axe, pickaxe and repair tools but it only needs one slot in your inventory. With mods and points in Miner 69 it is not even that weak. And if I want to dig up something and I don't have my pickaxe or auger with me, I quickly make myself a stone shovel. Works as well.
I found a Q6 Blunderbuss with ammo during a T5 quest today. So I put it on my belt and used it for the rest of the quest. I play on Nomad difficulty and a Blunderbuss rips the head off most zombie at point blank range if you have points in Boomstick. But even if the zombie survives this, he' usually winded or stunned. That's why the Blunderbuss is still a serious weapon in the endgame.
I mean sure its useful and just a regular tool just like every other tutorial item in any game, even those terrible white rank weapons in mmo's are useable and count as regular weapons but that still does not change the fact that its the bottom line of all equipment, something what by game design should be thrown out the moment you find the next tiers.
To me it barely makes any sense that im we are only still using in steel age but a T6 stone axe performs better than a T1 iron axe. It also doesnt make much sense that the stone axe is this big of a multitool but at the moment you reach the iron age now you need to have 2-3 tools for the same function as the stone axe. It feels like its an overloaded tutorial item what was designed to ease up the early gameplay before the players are getting thrown into the actual survival.