It's not a hammer subscription, it's hammering-as-a-service. You ship them the nails and wood, they ship you back the nails hammered into the wood. You don't have to worry about the complexity of storing or using a hammer anymore, let alone the difficulty of selecting the right hammer, it all just works. They charge extra to sell you the nails and wood, to avoid the complexity of packing and shipping your nails and wood.
They have strict specifications about the types of nails and wood that they can hammer, but they're not documented anywhere. If you send them the wrong type of nails or wood, they'll put them both into an industrial shredder and send you back the dust, because technically the nails have now been integrated with the wood.
Their free plan will let you hammer in 5 nails per month into a single piece of wood, but you can't use a different piece of wood each month. For $30/month you get 50 nails, and up to 5 pieces of wood, or for $60/month you can get 120 nails and unlimited pieces of wood, and two-factor (they'll call you before they hammer in the nails, and ask where you actually want the nails hammered). If you want to have unlimited nails, you have to contact them for enterprise pricing.
They will also sell the measurements of your wood and the nail positions to other carpenters.
If you need to build stuff out of wood, you have three options: buy something pre-made, hire someone to build it for you, or hire a team of carpenters to build it in house. Arguably, the third option should be your last choice.
Stretching the metaphor a bit, sometimes it makes sense to hire a team of carpenters, but contract out or buy pre-built a few particular parts that are particularly difficult or complicated.
That's essentially what these SaaS products are supposed to offer. The problem is not that they exist, the problem is that it can be difficult to know when you need or don't need any particular product.
