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.
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.