A common joke amongst software developers is:
“IOT…The ‘S’ stands for security!”
As you probably noticed, there is no ‘S’ in IOT. Likewise, there is no security. These devices are constantly being outed for security flaws.
If the device is more than about 2 years old, the manufacturer is unlikely to patch newly exposed flaws. Instead, they tell you to buy the latest model.
Many of them deliberately use only proprietary protocols, so you have to use their service, which is rarely free.
Those are just a few reasons we hate IOT.